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Arrays of zinc oxide (ZnO) nanorod (NR) were fabricated in a vertical axis direction through the two-step method of seed layer’s deposition and growth of the NR. The seed layer was applied by spin coating with a three-time repetition (n) and rotational speed (v) at 3000 rpm. After the seed layer had grown, ZnO NRs were grown with a growth solution made by combining one zinc source with one hydroxide source. There were two different zinc sources, i.e., zinc acetate dehydrate and zinc nitrate hexahydrate and, for comparison, zinc acetate (ZA) and zinc nitrate (ZN) were each combined with the same hydroxide source, hexamethylenetetramine (HMT). Later, the growth solutions were processed by the chemical bath deposition (CBD) method using a waterbath machine. The CBD method was started at room temperature until it reached the designated temperature at 85°C. At that point, the growth time was calculated from the zero-minute condition. It was found that ZnO NRs had already grown at a thickness of about 100 nm for both ZA and ZN sources. The growth time varied at 15, 60, 90, and 120 minutes after the zero-minute point. By using two separate and independent zinc sources while growing ZnO NRs at various growth periods, several ZnO NRs’ thicknesses were controlled. According to a paper by Lee et al., the lower thickness of ZnO NRs boosted the charge transfer properties of perovskite solar cells (PSCs) because the series resistance between ZnO/perovskite interfaces was lessened. Scanning electron microscopy (SEM) images were observed to analyze the morphological shape of the ZnO NRs. X-ray diffraction (XRD) profiles were characterized to obtain the data for ZnO NR crystallinity. Full width at half maximum (FWHM) analysis was performed at the (002) ZnO peak to calculate the crystal size of the peak. From the results, the smallest crystallite sizes for ZnO NRs grown from ZA and ZN sources were 10.70 nm and 19.29 nm, respectively, which would be the most suitable condition for PSC application.

The characteristics of nanocomposite titania/reduced graphene oxide (TiO2/rGO) deposited on a glass substrate with potential application in the energy harvesting device of perovskite solar cell has been examined. The active material TiO2 was deposited on top of a fluorine-doped tin oxide glass substrate via a spin coating method. Reduced graphene oxide (rGO) was then coated onto TiO2 layer to form a nanocomposite TiO2/rGO. Formation and crystal structure of the layer were characterized using X-ray diffraction (XRD), whereas the surface morphology was examined using a field emission scanning electron microscope (FE-SEM). A structural study from X-ray showed that the two phases of TiO2 and rGO are detected, whereas the morphological examination showed that the layer had been homogeneously deposited on the glass substrate. The performance of TiO2/rGO as an electron transport layer in the perovskite solar cell device fabricated with chloride modified perovskite (CH3NH3(Pb/Zn)Cl2I) showed different characteristics with different concentrations of TiO2 and rGO. The highest efficiency of 3.8% was obtained from the composition of 0.0325 M TiO2 and 0.5 vol.% rGO.

Platinum is the most effective counter electrode for use in dye-sensitized solar cells (DSSC). However, as platinum is very expensive, its price impedes its broad use as a DSSC counter electrode. As an alternative, carbon has been used for this purpose. In this study, carbon has been successfully pyrolyzed from the precursors of table sugar and sucrose through a chemical process, i.e. the dehydration of the precursors with sulfate acid followed by a pyrolysis process, and used as Pt-less counter electrode in a DSSC device. The as-synthesized carbon was characterized using X-ray diffraction (XRD) to obtain crystal structure information and a scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX) was employed to carry out morphological and compositional examination. The material activity and performance of the counter electrode in the DSSC device were analyzed using a semiconductor parameter analyzer through current–voltage characteristic curves (I-V). The results show that the precursors of table sugar without the addition of a metal catalyst and with initial heat treatment at 300°C for 1 hour, and of sucrose with a catalyst could produce carbon with a particle size of around 600–900 nm. The I-V curve characteristic of the DSSC device assembled using carbon produced from sucrose as a counter electrode resulted in a power conversion efficiency (PCE) of only 0.041%, whereas the DSSC device assembled using carbon produced from table sugar as a counter electrode exhibited a good performance with a PCE of 3.239%, almost equivalent to that of platinum paste with a PCE of 4.024%. This result is promising in terms of using a cheap source of carbon for the Pt-less counter electrode.

We are developing a solar powered system (SPS) on LAPAN Surveillance UAV - 03 (LSU-03). It is developed for marine monitoring to support marine security from illegal fishing. A longer time is needed to optimize the monitoring missions. This is strongly supported by Indonesia’s sunlit lands throughout the year so long-distance targets and wide area coverage can be achieved. The total power required is 96 Watts per hour. Therefore, it is very important to fulfill the power to fly for 6 hours. The solar powered system consists of solar module, maximum power point tracking (MPPT), and battery. The system development is to regenerate the power. A hardware design and terrestrial measurement of SPS is presented. It was conducted in Aeronautics Technology Center – LAPAN, Bogor. According to the results, the development of solar powered system gave 12.76 percent efficiency. The I-V graphics and battery charging time is presented. The SPS was able to charge the battery 8 Ah for 60 minutes. Therefore the SPS satisfy the power requirement for LSU-03 onboard electrical system.We are developing a solar powered system (SPS) on LAPAN Surveillance UAV - 03 (LSU-03). It is developed for marine monitoring to support marine security from illegal fishing. A longer time is needed to optimize the monitoring missions. This is strongly supported by Indonesia’s sunlit lands throughout the year so long-distance targets and wide area coverage can be achieved. The total power required is 96 Watts per hour. Therefore, it is very important to fulfill the power to fly for 6 hours. The solar powered system consists of solar module, maximum power point tracking (MPPT), and battery. The system development is to regenerate the power. A hardware design and terrestrial measurement of SPS is presented. It was conducted in Aeronautics Technology Center – LAPAN, Bogor. According to the results, the development of solar powered system gave 12.76 percent efficiency. The I-V graphics and battery charging time is presented. The SPS was able to charge the battery 8 Ah for 60 minutes. Therefore the SPS satisfy...

Non-degenerately doped lateral nanoscale p-n and p-i-n silicon-on-insulator devices have been fabricated and characterized at room temperature (297 K). In both types of devices, p-type Si substrate is used as a backgate to modify the potential in the top Si layer in both forward- and reverse-bias regimes. In the forward-bias regime, both types of devices exhibit negative differential transconductance (NDT), with the current peak position and level controlled by the backgate and anode voltage. In the reverse-bias regime, the devices exhibit a sharp current increase as a function of the backgate voltage, which is a signature of the band-to-band tunneling (BTBT) mechanism. These findings suggest that NDT and the sharp increase of current, induced by the contribution of the BTBT mechanism, can be achieved even in non-degenerately doped backgated diodes, which opens new possibilities for BTBT-based functionalities, benefiting from a simple design and CMOS compatibility.

A highly sensitive (at the picogram order) Al–doped–ZnO nanorods (AZNRs)–coated resonant microcantilever (MC) for carbon monoxide (CO) gas sensing, operable at ambient temperature and under humid condition was synthesized. The ZnO nanorods (ZNRs) were grown on the MC surface by using the hydrothermal method and doped by aluminum (Al). The sensitivities of un–doped and Al–doped ZnO nanorods for various CO gas concentrations were investigated by measuring the changes in the resonant frequencies and the Q–factor analysis of the vibrating MCs. The mechanisms of the remarkable enhancement of the sensitivity of the AZNRs–coated–microcantilever to CO were thoroughly investigated and discussed on the basis of energy gap between the highest occupied molecular orbital (HOMO)–Lowest occupied molecular orbital (LUMO) of AZNRs and CO, active surface area of AZNRs, and the interaction of water vapor on AZNRs surface with CO.

In this research, ZnO nanorods (NRs) have been fabricated for perovskite solar cell (PSC) application. An issue about the use of ZnO material for PSC application is lower photovoltaic outputs than TiO2 material. Such outcome is due to unstable ZnO/perovskite interface. Other factor is due to partial coverage of the perovskite over the ZnO material. By using 1-step method and mixture of DMF and DMSO as the solvent for perovskite solution, complete coverage of the ZnO NR was achieved. Multiwalled carbon nanotubes (MWCNTs) and copper iodide (CuI) were used as hole transport materials (HTMs) for comparison purpose. The experiment and characterization were done in Shizuoka University, Hamamatsu campus, Japan. The ZnO NRs were grown by implementing 2-steps method of seed layer deposition by spin coating and NRs growth through chemical bath deposition. Methylammonium lead iodide (CH3NH3PbI3 or MAPbI3) perovskite was grown through 1-step method by mixing equimolar lead iodide (PbI2) and methylammonium iodide (CH3NH3I or MAI) in DMF and DMSO solvents (volume ratio of 7 to 1 for DMF and DMSO, respectively). The current-voltage (I-V) curve for both materials showed higher JSC and VOC for MWCNTs at 5.34 mA/cm2 and 0.21 V, respectively compared to CuI materials (JSC = 3.40 mA/cm2 and VOC = 0.14 V). Lower VOC is the result of higher series resistance due to non-passivated ZnO/MAPbI3 interface. Another factor to consider is recombination of electron and hole at the interface. MWCNT material is an alternative material to act as HTM because of high conductivity and lower electrical resistance compared to CuI. Complete coverage of the perovskite over ZnO material helped improving the production of photogenerated electrons.

In this paper we report the results of OLED (organic light emitting diodes) fabricated using a completely vacuum free lamination method. Aluminum foil purchased from office supply stores is used as a cathode. Anodes are prepared from three different materials, Indium Thin Oxide (ITO), Fluorine doped Thin Oxide (FTO), and TC-07S (Denshi Kako, Co., LTD). Three anode materials were grown on three different types of substrates, glass, PET, and lamination plastic. Poly (9.9-dioctylfluorenyl) (PFO) which is used as an emissive layer was coated on pre-cleaned aluminum foil by spin coating method. The anode and cathode part are laminated under heated laminator at 130°C. We found that OLEDs fabricated using TC-07S as anodes and lamination plastics as substrates produce the best optical characteristics. The effect of TC-07S thickness on electrical characteristics was also examined. We found that the thicker the TC-07S layer caused higher currents level but not significantly increase the light intensity.

This paper present simple and inexpensive solar charge controller (SCC) using 8-bit microcontroller ATtiny85. The SCC using a pulse width modulation (PWM) signal to transistor and MOSFET to control current that generated by the microcontroller. The battery voltage state also monitored using a series resistor paralleled to the battery and the voltage drop connected to the microcontroller. The design of SCC consists of 3 major part i.e. microcontroller, current driver, voltage sensing. The purpose of measurement is to know the characteristics of 2 charging modes, mode 1 (one) and mode 2 (two), that occur in the system created. The measured data is the battery voltage as independent variable, and the solar panel’s voltage, the current that flow towards battery and the power provided for charging. Measurements are conducted from the battery voltage state of 7.84 V to 8.4 V. The results show that the solar charge controller using 8-bit microcontroller ATtiny85 was successfully managed to provide current and voltage according to expected design with 400 mA, 8.9 V for the first charging case and 150 mA, 12 V for the second charging case.

A solar street lamp is a lamp technology that utilizes solar cell to obtain electrical energy during the daylight hour by solar radiation and then use the electrical energy to provide light at night. Semiintegrated lamp tries to overcome complicated installation and expensive price of normally solar street lamp. Semi-integrated solar street lamp only integrated solar cell, controller, and battery, while lamp is separated using cable. This configuration makes semi-integrated lamp cheaper and easier for installation that is suitable for rural area. Therefore, in this paper we develop semi-integrated type of solar street lamp. The illumination of semi-integrated lamp was measured using lux meter. The power of the lamp was calculated to meet the energy needs for 12 hours. The results show that the semi-integrated solar street lamp with low power LED ~2W has been successfully developed. The solar lamp can be automatically turned on for around 12 hours, from 5:50 PM to 5:31 AM (UTC+7). The illumination average of the lamp is 17.42 lux with 6.97 lux deviation. The measurement result of illumination shows that the solar street lamp has maximum distance of more than 140 cm with 230 cm high of lamp.

Single-electron tunneling (SET) transistors have been studied for the past several decades because they are promising for low-power consumption and fundamental-level control of charge. The quantum dots (QDs) that are the main part of an SET transistor have been demonstrated in a variety of materials, but recently dopant-atoms in silicon have also been shown to work as QDs. However, a single conventional dopant-atom has usually a shallow ground state energy level below the conduction band edge (∼45 meV). This means that the tunnel barrier is relatively low and thermally-activated current can flow over the barrier. Therefore, the operation of dopant-atom SET transistors remains limited to low temperatures. In this work, we statistically analyze the key factors for raising the SET operation temperature up to room temperature (>300 K).

Organic light emitting diodes (OLED) are considered to be a promising candidate for light sources as well as for flat panel display because of their numerous advantageous. Two important parameters of an OLED among many other parameters to measure OLED performance are operating voltage and luminance. Those two parameters are believed to be strongly influenced by an anode and cathode workfunction of materials used as electrodes. In this paper, we study the effect of anode and cathode workfunction on the operating voltage and luminance of a single emissive layer organic light emitting diode. Devices with five different cathodes: Aluminum (Al), Calcium (Ca), Magnesium (Mg), Argentum (Ar), and Cuprum (Cu) and three different anodes: Indium Thin Oxide (ITO), Poly-(3,4-Ethylenedioxidythiophene)-Poly (Styrene Sulfonate) (PEDOT:PSS), Zinc Oxide (ZnO) are compared and analyzed. A 2 nm thick of Polyfluorene (PFO) is used as an emissive layer. SimOLED is used to simulate and analyze both electrical and optical characteristics. Current voltage luminance (IVL) characteristics are simulated under forward biased from 0 to 10 V. We found that the use of anode with higher workfunction can reduce operating voltage as well as increases device luminance. On the other hand, the use of lower workfunction of cathode can reduce operating voltage however it is not always increasing device luminance. The decrease of the operating voltage by increasing anode workfunction and decreasing cathode workfunction are ascribed to the barrier lowering of the holes and the electrons respectively.

We have recently reported single-electron tunneling (SET) via a-few-donor QDs at high temperatures in high-concentration selectively-doped SOI-FETs. A central QD works by SET mechanism above 150 Κ at small source-drain bias due to enhanced tunnel barrier. For tuning the tunnel barrier, it becomes critical to understand the impact of the donor-QD location on the SET transport. Here, we report the possibility of probing donor-QDs from center to near the lead edge using high-bias stability diagrams. We also observe and model the changes due to purposely shifted positions of the selectively-doped area.

Resonance frequency shift of a zinc oxide- (ZnO-) functionalized microcantilever as a response to carbon monoxide (CO) gas has been investigated. Here, ZnO microrods were grown on the microcantilever surface by a hydrothermal method. The measurement of resonance frequency of the microcantilever vibrations due to the gas was carried out in two conditions, that is, gas flow with and without air pumping into an experiment chamber. The results show that the resonance frequency of the ZnO-functionalized microcantilever decreases because of CO in air pumping condition, while it increases when CO is introduced without air pumping. Such change in the resonance frequency is influenced by water vapor condition, and a possible model based on water-CO combination was proposed.

As electronic device dimensions are continuously reduced, applied bias conditions significantly change and the transport mechanisms must be reconsidered. Tunneling devices are promising for scaled-down electronics because of expected high-speed operation and relatively low bias. In this work, we investigated the tunneling features in silicon-on-insulator lateral nanowire pn junction and pin junction devices. By controlling the substrate voltage, tunneling features can be observed in the electrical characteristics. We found that the minimum substrate voltage required for tunneling to occur in pn junctions is higher as compared with pin junctions. The main cause of these effects relies in the difference between the doping profiles, since the pn junctions contain a co-doped region, while the pin junctions contain an i-layer.

Organic Light Emitting Diode (OLED) merupakan divais fotonik yang tersusun dari katoda sebagai sisi negatif, anoda sebagai sisi positif, dan sebuah lapisan emissive dari bahan organik yang dapat memancarkan cahaya ketika penghantar diberi arus listrik. Karakteristik arus yang dibutuhkan harus sesuai dengan karakteristik tahanan sehingga dapat menghasilkan fabrikasi OLED yang optimal. Teknik laminasi merupakan salah satu teknik yang digunakan dalam pembuatan Organic Light Emitting Diode (OLED) dengan cara menempatkan struktur OLED pada plastik laminasi. Tahun 2015, Adnan Fatahillah Afiff [1] memfabrikasi Organic Light Emitting Diode (OLED) menggunakan teknik laminasi tetapi hasil fabrikasi belum dapat memancarkan cahaya. Ada beberapa hal yang mempengaruhi karakterisasi OLED saat fabrikasi yaitu suhu laminating, waktu ultrasonic cleaning , dan kecepatan rotasi spin coating . Ketiga faktor tersebut akan mempengaruhi karakteristik arus yang dihasilkan dan dapat memaksimalkan fabrikasi OLED. Oleh karena itu diperlukan penelitian terkait pengaruh ketiga faktor tersebut terhadap karakteristik arus listrik pada OLED. Langkah-langkah yang dilakukan adalah menggunakan teknik laminasi dan memvariasikan waktu ultrasonic cleaning , kecepatan rotasi spin coating , dan suhu laminating. Arus listrik yang mengalir pada Organic Light Emitting Diode OLED dapat mencapai nilai paling tinggi pada saat waktu ultrasonic cleaning selama 15 menit, suhu laminating sebesar 130 o C, dan kecepatan rotasi spin coating 4500 rpm.

Coulomb-blockade transport via donors working as quantum dots (QDs) in Si nano-transistor channels opens new pathways for atomic-level applications, but position-control of such QDs remains challenging. Here, we demonstrate that multiple-donor cluster-QDs can be formed by CMOS-compatible selective-doping, as observed from Coulomb-blockade transport at low temperature (T = 5.5 K). While at high gate voltage electron tunneling takes place via extended QDs, likely due to line edge roughness of the nanoscale channel, at low gate voltage tunneling occurs via a cluster of intentionally-doped donors. For the interpretation, we introduce a model of an isolated donor-cluster as a QD with voltage-dependent tunnel resistances.

The characteristics of nano rosette TiO2 hydrothermally grown on a glass substrate with potential application in perovskite solar cell has been examined. Nano rosette TiO2 was synthesized through deposition on top of a fluorine-doped tin oxide glass substrate via hydrothermal reaction at 170°C for 6 hours. Formation and growth mechanism were characterized using X-ray diffraction (XRD), whereas the morphology was examined using a field emission scanning electron microscope (FE-SEM). The results showed that the formation of nano rosette TiO2 has been completed after 6 hours. Structural study from X-ray diffraction also showed that the crystal structure formation has been completed after 6 hours. This nano rosette TiO2 was tested for its performance as an electron transport layer (ETL) in the perovskite solar cell device. For this purpose, the perovskite CH3NH3PbCl2I 0.8 M was deposited on top of the ETL layer and the performance was tested using a semiconductor parameter analyser (SPA). The result showed an efficiency of about 3.4%, which is promising for the next development.

We have demonstrated that Si single-electron SOI-MOSFETs with multidots channel have attractive new functions such as single-photon detection. Multidots formed by nanoscale selective oxidation of thin SOI layer have been used for photon detection. Most recently, we have investigated photon detection capabilities of FETs having phosphorus (P)-doped channel. In such P-doped FETs, each P donor works as a quantum dot for electrons and single-electron transport is achieved by tunnelling through donor potentials. Using such P-doped FETs, single-photon detection has been demonstrated. Furthermore, in order to directly observe the spatial landscape of even a single-dopant potential, we have developed low-temperature-Kelvin probe force microscopy (LT-KFM) and succeeded in detecting a single-dopant potential in the channel region. In this paper, we present results of photon-induced random telegraph signals in crystalline-dot-type and donor-dot-type multidot single-electron SOI-MOSFETs, and direct observation of a single-dopant potential by LT-KFM.

Dye is an important factor in determining the efficiency of a dye-sensitized solar cell (DSSC) device. One of the dyes derived from natural resource is anthocyanin. At the same time, one of the natural resources containing anthocyanin is a tropical plant called mangosteen. In this work, the characteristics of anthocyanin extracted from mangosteen pericarps using different solvents have been examined. The anthocyanin was extracted from mangosteen pericarps using various different solvents, i.e. dry ethanol, ethanol containing 1% HCl, and ethanol containing 1% acetic acid. Absorption characteristic of dye extracted from different solvents was determined using ultraviolet-visible spectroscopy (UV-Vis). Fourier transform infrared (FTIR) was used to examine the functional groups of the extracted dye. Visible light absorption and photo-sensitizing characteristics of the extracted natural dye were then investigated through their applications in a DSSC device. The results from infrared characterization showed that all of the extracted dyes indicated the same tendency with the characteristic of anthocyanin. At the same time, the UV-Vis examination revealed that the dye extracted using solvent HCl 1% acidified ethanol was found to have a visible light absorption at a wavelength of 533 nm. This result indicated that HCl 1% acidified ethanol was the best solvent to extract anthocyanin from mangosteen pericarps. The activity of the DSSC device sensitized using the extracted dye through a photocurrent-voltage examination showed a power conversion efficiency of 0.23% and 0.18% for the device using the commercial dye and the mangosteen extracted dye, respectively. This result is quite convincing and promising for the next DSSC device development using natural dye extracted from mangosteen pericarps.

One device being developed as an alternative source of renewable energy by utilizing solar energy source is dye-sensitized solar cells (DSSC). This device works using simple photosynthetic-electrochemical principle in the molecular level. In this device, the inorganic oxide semiconductor of titanium dioxide (TiO2) has a great potential for the absorption of the photon energy from the solar energy source, especially in the form of TiO2 nanoparticle structure. This nanoparticle structure is expected to improve the performance of DSSC because the surface area to weight ratio of this nanostructures is very large. In this study, the synthesis of TiO2 nanoparticle from its precursors has been performed along with the fabrication of the DSSC device. Effort to improve the size of nanocrystalline anatase TiO2 was accomplished by low hydrothermal treatment at various temperatures whereas the crystallinity of the anatase phase in the structure was performed by calcination process. Characterization of the materials was performed using X-ray Diffraction (XRD) and scanning electron microscope (SEM), while the DSSC performance was examined through a high precision current versus voltage (I-V) curve analyzer. The results showed that pure anatase TiO2 nanoparticles could be obtained at low hydrothermal of 100, 125, and 150 °C followed by calcination at 450 °C. The best performance of photocurrent-voltage characteristic was given by TiO2 hydrothermally synthesized at 150 °C with power conversion efficiency (PCE) of 4.40 %, whereas the standard TiO2 nanoparticles has PCE only 4.02 %. This result is very promising in terms low temperature and thus low cost of anatase TiO2 semiconductor preparation for DSSC application.

Curcumin has known to have a long intense wavelength absorption in the visible region ranging from 420-580 nm. Because of that, curcumin is a promising material for use in dye sensitized solar cells. In this work, curcumin was extracted from turmeric (Curcuma longa L.) through a simple extraction technique using different organic solvents, i.e. acetone, methanol, and ethanol. The results from the extraction were applied as a sensitizer in dye sensitized solar cell applications. Suitable solvent for extraction that could give high efficiency in DSSC device were analysed. Characterization of the dye was performed using Fourier transform infrared (FTIR) and ultra violet-visible (UV-Vis), while the performance of DSSC was analysed through a simple current and potential different (I-V) curve analyser. The infrared results showed that all of the turmeric extracted dyes have the same tendency with the characteristic of curcumin. UV-Vis absorbance characteristics of the curcumin natural dye extracted using acetone, ethanol and methanol has the same tendency with plateau-like absorbance peak at around 490, 492, and 505 nm, respectively. The maximum power conversion efficiency (PCE) is found to be 7.88% obtained from the solvent of ethanol whereas the PCE obtained from other natural dyes extracted using acetone and methanol are found to be low, 2.23% and 1.25%, respectively. This finding is convincing in terms of efficiency in which the value from the dye extracted using ethanol has higher efficiency than that of the commercial organic dye RK1 with a PCE of 4.02%.

In this paper we study the effect of Hole Transport Layer NPB (N,N′-diphenyl-N,N′-bis(1-naphtyl)-1,1′-biphenyl-4,4″-diamine) and Electron Transport Layer on the performance of a single layer of Blue Organic Light Emitting Diode. Three different structures are analyzed and are compared to the reference structure. SimOLED is used to simulate and to analyze both electrical and optical characteristics. We found that the addition of 1 nm hole transport layer significantly improve the luminance by more than 1.5 times which is ascribed to the increase of the hole injection leading to the balance charge in the emissive layer. On the other hand, the application of 1 nm electron transport layer provide lower operating voltage which become more significant when both hole transport layer and electron transport layer are combined. The proposed structure reaches a luminance of 49,543 cd/m2 at 10 V.

Today, institutions of higher education play increasingly active roles in helping achieve a sustainable society. This study aims to demonstrate the lessons learned in the development of a green environment at the Faculty of Engineering, University of Indonesia. This paper reviews the development of the necessary supporting infrastructure and discusses opportunities and challenges in establishing a green environment. The availability and condition of groundwater sources are identified, and the process by which canteen wastewater is treated by phytoremediation is described. Additionally, composting and recycling of solid wastes are encouraged in communities, and a model for an energy-efficient classroom is discussed. Three lessons learned are discussed: a focus on defining the program, continuous education and monitoring, and sources of funding. The implications of this study for relevant practices are also identified.

The reduced dimensionality of present electronic devices brings along changes in the dopant distribution in the device channel, in which only a small number of dopants exist. Recent studies demonstrated that individual dopants strongly affect the electrical characteristics of nanoscale transistors. On the other hand, nanoscale pn junctions, building unit of more complex devices, have not been sufficiently studied from this viewpoint. In this work, we report several experiments that we carried out on nano-pn junctions in which the individuality of dopants is prominently observed. In electrical characteristics, we report, under various conditions, random telegraph signals (RTS) related to dopants as traps. The dynamic behavior of the depletion region of nano-pn junctions is also characterized by Kelvin probe force microscopy. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6312

We study nanowire silicon pin and pn-junctions at room and low temperature. Photovoltaic effects are observed for both devices at room temperature. At low temperature, nanowire pn-junction devices show their ability to detect single photon. This ability was not been observed for pin devices. Phosphorus-boron dopant cluster in the depletion region is considered to have the main role for single-photon detection capability. Fundamental mechanism of dopant-based single-photon detection in nanowire pn-junction is described in details.

Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.

This report is focused on the linear region of I-V characteristics of nanoscale highly-doped p-i-n diodes fabricated within ultrathin silicon-on-insulator (SOI) structures with an intrinsic layer length of 200 nm and 700 nm under a forward bias at a temperature range from 50 K to 250 K. The doping concentrations of Boron and Phosphorus in SOI p-i-n diodes are high, 1×1020 cm-3 and 2×1020 cm-3, respectively. The linearity of I-V characteristics of the p-i-n diodes under a certain forward bias voltage range and temperature range from 50 K to 250 K indicate these devices are suitable for low temperature sensing purposes. We conclude that highly-doped p-i-n diodes produce a higher current as the temperature decreases under a certain bias voltage range. Nanoscale diodes with longer and wider intrinsic layers generate higher currents under a certain range of bias voltage and low temperature measurements.

Solar cell is optimized to convert solar radiation to electrical current with conversion efficiency as high as possible. Due to their superior performance compared to conventional silicon devices we used the Si/sub x/Ge/sub 1-x/ strained layer for increasing the efficiency of solar cell device. By using simulation's tools, i.e. pc1d version 5.6, we investigate and analysis the performance of Si/sub 0.2/Ge/sub 0.8//Si solar cell, especially open circuit voltage, short circuit current, fill factor which will affect the efficiency of the device. We also compare it with conventional silicon solar cell in order to examine their performances and the thickness of both device structures. The Si/sub x/Ge/sub 1-x/ strained layer we applied contents 80% germanium. Results show that by inserting Si/sub 0.2/Ge/sub 0.8/ strained layer in device structure open circuit voltage and short circuit current has been optimal and the thickness of the device compared to conventional silicon solar cell is 1/17 times.

We study the photoresponse of Si nanoscale p–n and p–i–n diodes. As a result, we find a photon-sensitive multilevel random telegraph signal (RTS) in p–n diodes, but not in p–i–n diodes. From this fact and analysis of current jumps in the RTS, the multilevel RTS is ascribed to single photocarrier charging and discharging in a donor–acceptor pair in the depletion region. Thus, it is found that a donor–acceptor pair plays an important role in p–n junctions, while, according to our previous report, a single donor (acceptor) works as an electron (hole) trap in junctionless field-effect transistors.

We have comparatively studied the effects of electron injection in individual phosphorus-donor potential wells at 13 K and 300 K by Kelvin probe force microscopy in silicon-on-insulator metal-oxide-semiconductor field-effect-transistors. As a result, at 13 K, localized single-electron filling into the phosphorus-donor potential well is found, reflecting single-electron tunneling transport through individual donors, whereas at 300 K, spatially extended and continuous electron filling over a number of phosphorus-donors is observed, reflecting drift-diffusion transport.

We study interaction of single-electron current and incident photons in nanometer-scale phosphorus-doped silicon-on-insulator field-effect transistors. Trapping events of a photoexcited-electron by a trap donor are observed as random telegraph signals in single-electron-tunneling current flowing through a current-path donor. Trapping causes a potential change at the current-path donor, inducing a current change. An opposite current change is caused by electron detrapping from the trap donor to the current-path donor. This indicates that only a few donors (two donors in this study) work in the interaction between single-electron transport and photoexcited-electron trapping, even in the presence of many donors.