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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.

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.

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.

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.

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.

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.

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.

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.

Electrons in a single electron transistor (SET) are transported one by one from source to drain based on the coulomb blockade mechanism. The transport rate is sensitively influenced by the presence of event a single electron charge located near the quantum dot. Based on this characteristic, we propose a Double Quantum Dot (DQD) SET to manipulate the presence of an electron in Quantum Dot (QD) as an implementation of a single-electron logic concept. The existence of an electron in the QD is used to represent logic 0 (no electron in QD) or logic 1 (an electron in QD). The logic states are sensed by a SET charge detector. Design of circuit based on DQD and SET charge detector are simulated by using SIMON 2.0 software. From the simulation, we have successfully developed a two-bit logic circuit by controlling the presence of an electron in DQD. We found that the existence of an electron in QD can be controlled by application of a gate voltage larger than 190µV. Gate should be separated from QD by a non-tunnel capacitor of 500 aF. No larger than 1 aF of interdot tunnel capacitance is required to isolate the QD from one to another. The existence of an electron in QD is successfully detected by SET based charge detector.

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.