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Controlling the defect in the perovskite absorber layer is a very crucial issue for developing highly efficient and stable perovskite solar cells (PSCs) as it exhibits the existence of unavoidable defects even after the careful fabrication process. In this study, the presence of defects in the perovskite layer has been evaluated through the analysis of its structural and optical properties. Then the investigations on the impact of defect density on perovskite absorber layer and its associated solar cell parameters have been carried out by numerical simulation utilizing SCAPS-1D software. Besides the defect density, the thickness of the absorber layer has also been varied to find optimum values of cell parameters. It has been found that when the thickness of absorber and shallow defect density is increased from 200 nm to 800 nm and 1 × 1013 cm-3 to 1 × 1018 cm-3 respectively, power conversion efficiency (PCE) is varied from 26.7% to 0.90%. However, when the thickness and deep defect density are raised from 200 nm to 800 nm and 1 × 1013 cm-3 to 1 × 1016 cm-3, respectively, the PCE is varied from 19.3% to 6.15%. It is revealed that optimum absorber thickness is 550 nm and the tolerances of shallow level and deep level defect density are 1 × 1017 cm-3 and 1 × 1015 cm-3, respectively.

In view of the problems existing in the teaching of higher mathematics in universities, such as more teaching contents, different students' foundation and less course hours. this paper studies the higher mathematics teaching reform under the environment of smart classroom, integrates information technology and mathematics teaching in a deep level, so as to solve the pain points of mathematics teaching in universities. To further improve the efficiency of using smart classroom to carry out higher mathematics teaching in universities, this paper analyzes some learning theory, structure and the characteristics of smart classroom, then constructs a higher mathematics course teaching model based on the smart classroom. Higher mathematics teaching mode based on smart classroom is a kind of teaching method that students like, which has greatly improved teaching efficiency and students' performance.

In this paper we present results of DLTS investigating HIT solar cells. Analysis of DLTS spectra gave deep level activation energies and concentrations. However this method hardly allows to find spatial localization of these defect states. Therefore here we developed a method to find separated values of recombination rates corresponding to different spatial regions: a-Si layers, interfaces, depletion region and quasineutral base. We quantity found that recombination in the depletion region and at the interfaces strongly dominate and affect efficiency of the cell. Here we show that this technique is useful for interpretation of DLTS data and investigation of recombination processes in HIT solar cells.

Homogeneous transformation receives considerable attention in recent years as it is essential for change detection in heterogeneous images. However, most existing methods perform the homogeneous transformation based on low-level features. It leads to inaccurate homogeneous representations of the heterogeneous images and accordingly causes unsatisfied performance of change detection. To solve this problem, this paper presents a new model that utilizes deep- level features for homogeneous transformation instead of low-level features. Experimental results on real remote sensing data show that, the proposed method achieves an overall change detection accuracy of 95.91%, providing better performance than the existing methods based on low- level features.

Lima is facing rapid urban growth, including a rapid expansion of informal areas, mainly taking place within three peripheral cones. Most of the studies on that subject focused in general on informal settlements. Yet in this paper, we focus on two different informal types, graveyards and housing. They are experiencing complex, intertwined development dynamics due to a lack of land for housing and burials, causing social and public health problems. Housing invasions on burial grounds have never been systematically investigated. Yet, while challenging due to their morphological similarity, the detection of boundaries between graveyards and neighbouring and sometimes invading informal housing is essential, e.g., to prevent the spread of diseases. This study aims to distinguish those similar urban structures of which the visual features are very alike (e.g., rectangular shapes, same colours, organic organization). We used state-of-the-art Fully Convolutional Networks (FCNs) with dilated convolution of increasing spatial kernels to acquire features of deep level of abstraction on Pleiades satellites images. We found that such neural networks can reach a good level in mapping both informal developments with a F1-score of 0.819. Effective monitoring of such developments is important to inform planning and decision-making processes to allow interventions at critical locations.

This work demonstrates UV assisted probing of deep level traps in dielectric/GaN interface. The deep level donor traps lead to threshold voltage and gate leakage instabilities in GaN MISHEMTs. While UV exposure excites the deep traps, gate bias can sweep the trap energy state and trigger de-trapping. The recovery transient is evaluated to study the trap time constant. Besides, this work reveals a non-destructive technique to probe intrinsic traps as the UV exposure does not change the trap density across the device.

To facilitate sensor integration and provide a testbed for autonomous sense and react research, an onboard sensor processing and autonomy system has been developed for the REMUS 100 AUV using the Robot Operating System (ROS) and the REMUS RECON interface, which provides backseat control of the vehicle. An interface library, pyREMUS, has been developed to handle the REMUS RECON interface, and a ROS package, ros_remus, uses this library to provide a deep level of interoperability between the REMUS vehicle computer and other ROS-based subsystems. This system has been deployed on multiple REMUS 100 vehicles and it is currently used operationally for field research programs. Vehicles outfitted with this system have seen numerous deployments, where they have been used for seabed surveys, sensor evaluation, and engineering tests.

Deep-level traps’ capture and emission time constants are known to impact the GaN HEMT models' ability to reproduce the device behavior when subject to RF modulated signals. Since deep level traps' capture time constants are usually much shorter than current pulse duration, they are usually neglected as assumed infinitesimally short. This work demonstrates, through basic semiconductor physics and experimental results, that such an assumption may not be verified, therefore justifying the effort of modeling such time constants as they may fall within the low-frequency components of modern communication signals.

The impact of RbF incorporation after $CuIn_{1}-_{x}Ga_{x}Se_{2}$ (CIGS) growth on the electronic defects and device properties was investigated using various characterizations. Deep level transient/optical spectroscopy (DLTS/DLOS) shows the presence of two trap levels at Ev+0.57eV and Ev+0.98eV. XRD and XRF show no change in sample structure or composition, respectively. Finally, current voltage measurement indicates an enhancement of the device performance which is correlated with the other characterizations.

Deep-level defects in as-grown and annealed dilute nitride semiconductor GaInNAsSb solar cells grown by molecular beam epitaxy were investigated by admittance spectroscopy measurement and compared to determine the mechanism of post-annealing effects on improving the collection of photo carriers. The annealing was confirmed to be effective to decrease nitrogen-related defects in the as-grown GaInNAsSb sample as well as the background carrier concentration. This effect is considered to be mainly responsible for the improved collection of photo carriers. In addition, we found an optimal annealing temperature that suppresses the formation of new defects, leading to a remarkable improvement of the photo carrier collection.

In this paper, the impact of deep level traps on the I-V and C-V characteristics of InP/InGaAs heterojunction have been studied by introducing deep level traps in pre and post-irradiation samples. In this case, forward recombination current and junction capacitance in dependence of the deep level density and energy have been analyzed by TCAD simulation and experiments. The simulation results are in good agreement with the experimental results. The junction capacitance and recombination current both increase with the increasing of deep level density. Apart from this, the radiation induces deeper level traps, which contributes more to these increased trends.

With the decline in productivity in the mining industry it is crucial to reduce operational costs while still maintaining safe underground working conditions. A load shifting project was implemented on the refrigeration system of Mineshaft A as part of a demand side management (DSM) initiative. The DSM project over-performed by 0.5 MW, but an increase in service water temperature was measured over the Eskom evening peak periods. The chill dam temperature increased with more than 10 °C during load shifting. It was thus proposed that the surface refrigeration system of Mineshaft A be optimised in order to retain the energy savings, while improving service delivery. After an in-depth investigation it was found that both the pre-cooling towers and the control philosophy used to incorporate load shifting were very inefficient. It was thus proposed that the pre-cooling tower fans be repaired and the control philosophy be optimised by matching the evaporator flow rate of the fridge plants with the warm water flow rate into the surface hot dams. This resulted in lower pre-cool dam temperatures and, along with the optimised control philosophy, the chill dam temperature improved by a daily average of 3.9 °C. This improvement was realised even with the presence of a broken fridge plant in the surface refrigeration system of Mineshaft A. The load shift performance also increased with an average of 1 MW, realising an additional annual cost saving of R 375 000.

Analysis of existing theoretical concepts in low-frequency noise generation mechanisms in semiconductor barrier structures is performed. It is shown that investigation and simulation of voltage-noise characteristics offer an opportunity to calculate deep level parameters more precisely and to predict semiconductor devices reliability.

This paper highlights electrical characterization of Schottky structures prepared on AlGaN/GaN designed for HEMT's using Deep Level Transient Fourier Spectroscopy (DLTFS) method with electrical and optical excitation. In case of electrical excitation the density of minority and majority carrier traps had strong effect on the evaluation, whereas preliminary DLTFS with optical excitation (MCDLTFS) measurements made possible to identify minority carrier defects with higher precision. Parameters of two electron-like defects EL1 (0.47 eV), EL2 (0.54 eV) and three hole-like defects HL1 (1.13 eV), HL2 (0.93 eV) and HL3 (0.49 eV) were identified. HL1 andHL2 were confirmed by both methods: DLTFS and MCDLTFS. These are connected to a Carbon interstitial defect and well-know threading dislocations. Experimental results confirmed the benefits of different method utilizations in complex defect identifications.

In this work, a novel deep-impurity-level assisted tunneling technology with enhanced band to band tunneling (BTBT) probability is proposed and experimentally demonstrated. Through implanting deep level impurities in the tunnel junction, continuous deep level states can be introduced to facilitate the BTBT process for significant BTBT probability boosting. Compared with conventional tunnel diodes, the fabricated deep-impurity-level assisted tunnel diodes exhibit 7.8× and 23× current enhancement in P++/N+ and N++/P+ tunnel diodes respectively, showing its great potential for future current enhancement in tunnel FETs.

based on the analysis of studied physical processes, the amount of technical requirements to be met by measuring complex for research of the deep level defects in semiconductors have been formulated. Created complex is a flexible measuring system that can adapt to different measurement algorithms within Deep-Level Transient Spectroscopy (DLTS) and methods of obtaining of Capacitance-Voltage (CV) or Current-Voltage (IV) characteristics.

The impact of the composition of a 3-stage-process deposited CIGS on the deep level spectrum was investigated using deep level transient and optical spectroscopies to probe defects throughout the bandgap to have a complete picture of the defect spectrum. It is shown that the defect spectra depend strongly on the Ga/In ratio with both higher numbers of trap levels and higher trap concentrations (by >65%) on average in the higher Ga content films. These facts can likely explain the reduced CIGS solar cell efficiency at higher Ga content.

Traps in Cu(In, Ga)Se 2 (CIGS) deposited by listage and 3-stage co-evaporation processes were characterized using conventional deep level transient and optical spectroscopies (DLTS/DLOS) and scanning-DLTS to quantity and map the deep levels associated with the different growth approaches. Two defects were observed at E V + 0.44/0.50 eV and E V + 0.97 eV. The total deep level trap concentration was found to vary primarily due to the E V + 0.97 eV trap, which was ∼4X larger in the 1-stage sample. This large increase correlates with the reduced open circuit voltage and conversion efficiency typically observed in 1-stage co-evaporation grown CIGS, suggesting that controlling the presence and concentration of this level may be important to enable high-efficiency CIGS solar cells using simpler processes.

It was studied microplasma breakdown statistical delay in the green GaP:N light emitting diodes. It was detected unusual strong dependence of deep level traps on the avalanche breakdown statistical delay after changing their charge state with the voltage decreasing on the p-n junction in the temperature range 300–380 K. It was found out four deep level traps and determined their parameters.

The authors compared the influence of laser thermal annealing (LTA) and rapid thermal annealing (RTA) on dopant activation and electrical performance of phosphorus and arsenic doped n+/p junction. High carrier concentration above 1020 cm−3 as well as an I ON /I OFF ratio of approximately 105 and ideality factor (n) approximately 1.2–1.5 was achieved with LTA. However RTA revealed very high I ON /I OFF ratio approximately 107, and n close to 1. Non ideal behavior in LTA diodes is attributed to existence of deep level defects in the junction, contributing to leakage current. Meanwhile ideal behavior of RTA diodes is due to removal of defects in the junction during the high thermal budget.

We report on drive-level capacitance profiling (DLCP) measurements made on Cu(In,Ga)Se 2 solar cells. We observe that the deep level defect density and carrier concentration are correlated, with lower deep level defect densities and lower carrier concentrations associated with higher average Cu/III measured within the first half micron of the surface using Auger electron spectroscopy (AES).

South Africa's steep electricity tariff increases have forced the mining industry to be more cost effective. One way is by implementing demand side management (DSM) projects. Energy saving priorities focused mainly on mines with large energy consumption and long “life-of-mine”. If paybacks are short enough, it should be a feasible investment to implement DSM projects. This could extend the “life-of-mine” of marginal mines. To assist with investigations, procedures are introduced to estimate the potential savings and required capital costs. These procedures were developed by analysing previous projects implemented by the CRCED PTA research group. Energy cost savings strategies are proposed for the dewatering-, refrigeration- and water distribution systems. A case study is used to show the benefit of the proposed procedures. Since capital investment on marginal mines is limited, breakdowns and equipment failures may be frequent. This may negatively influence saving and project paybacks http://www.ieee.org/conferences_events/conferences/xplore_conference_proceedings.html

Deep level transient spectroscopy has been used to study the spatial properties of the N1-admittance feature in Cu(In, Ga)Se2 devices. By comparison to admittance spectra, the N1-admittance feature has been identified in deep level transient spectra. By varying the filling pulse voltage used to generate the deep level transient spectra, the spatial properties of the N1-admittance feature are determined. In particular, the N1-admittance feature is shown to arise from a uniformly distributed bulk defect in the sample studied.

In this paper we experiment with methods based on Deep Belief Networks (DBNs) to recover measured articulatory data from speech acoustics. Our acoustic-to-articulatory mapping (AAM) processes go through multi-layered and hierarchical (i.e., deep) representations of the acoustic and the articulatory domains obtained through unsupervised learning of DBNs. The unsupervised learning of DBNs can serve two purposes: (i) pre-training of the Multi-layer Perceptrons that perform AAM; (ii) transformation of the articulatory domain that is recovered from acoustics through AAM. The recovered articulatory features are combined with MFCCs to compute phone posteriors for phone recognition. Tested on the MOCHA-TIMIT corpus, the recovered articulatory features, when combined with MFCCs, lead to up to a remarkable 16.6% relative phone error reduction w.r.t. a phone recognizer that only uses MFCCs.

Degradation of low voltage power MOSFET electrical parameters induced by high field and subsequent avalanche mechanisms during multipulse UIS test is presented. Unclamped inductive switching (UIS) condition represents the harsh circuit switching operation for evaluating the “ruggedness”. Introduction of multi-pulse UIS test better corresponds to a real industrial situation where devices have to sustain several consecutive stress pulses. Strong degradation of CV curves without degradation of IV curves was observed after 6 millions of stress pulses was observed. Deep levels generated by hot carriers during UIS were studied using DLTS measurement set-up. Obtained deep level traps were taken into account for the numerical simulations to verify measurements

An algorithm of hypertext information categorization based on SVM was introduced. The algorithm divided a large data-set into many non-intersecting subsets during training period, in which the samples are trained according to the batch and then many classifications are constructed. The classifications are optimized by error correcting output codes (ECOC), which reduces the amount of documents to be studied in the deep level training phase. The application of this algorithm to hypertext information categorization underlines the theoretical results.

Experimental investigation of GaAs MESFET substrate batch effect on characteristics of ultra-short pulses exposure was carried out. The effect of differences substrate deep level concentration in MESFET under this exposure was simulated. These effects was investigated and described.

We argue for the importance of a real customer in a capstone project course via reporting experiences from over ten years period at University of Jyvaskyla (JYU), and providing also practical knowledge and theoretical underpinnings for such an arrangement. Based on our experience and empirical data, we underline that this arrangement is a chance for the students to increase their occupational identity. Theoretically our rationalization of the course arrangement proposes self-direction, empowerment, motivation, and deep level learning strategies for the students.

Semi-insulating (SI) InP obtained by iron phosphide ambient annealing has very low concentration of deep level defects and better electrical property than SI-InP annealed in phosphorus ambient. The defect suppression phenomenon correlates with Fe diffusion and substitution in the annealing process. Analysis of the experimental result suggests that a high activation ratio of incorporated Fe in InP has an effect of defect suppression in Fe-doped and Fe-diffused SI-InP.

We have investigated the temperature-dependent photoluminescence and deep-level defects in Be-doped, p-type In/sub 0.03/Ga/sub 0.97/As/sub 0.99/N/sub 0.01/ grown by radio frequency plasma-assisted solid source molecular beam epitaxy.

Slow current transients in a GaN MESFET are analyzed by two-dimensional simulation in which deep levels in a semi-insulating buffer layer is considered. It is shown that when the drain voltage V/sub D/ is raised abruptly, the drain current overshoots the steady-state value, and when V/sub D/ is lowered, the drain current remains at a low value for some periods, showing drain lag behavior. This drain lag is shown to become a cause of so-called current collapse in the GaN MESFET.

Spectral dependence of the photoionization cross sections for iron (Fe) acceptor doped in the liquid-phase-epitaxy-grown InP and In/sub x/Ga/sub 1-x/P (x=0.49) layers is determined by photocapacitance spectroscopy. The deep-level structures and the carrier-emission processes are precisely analyzed. For the crystal-field-split levels of Fe/sup 2+/:/sup 5/E and /sup 5/T/sub 2/, the fundamental transitions of /sup 5/E-/spl Gamma//sub 1/, /spl Gamma//sub 15/-/sup 5/E in InP:Fe, and /spl Gamma//sub 15/-/sup 5/E, /spl Gamma//sub 15/-/sup 5/T/sub 2/ in In/sub x/Ga/sub 1-x/P:Fe are adequately described by the Lucovsky-model calculation. The optical thresholds and the crystal-field-split energies are determined accurately. The small difference between the optical and thermal energies indicates that the Fe acceptor level is perturbed weakly by the lattice vibration in the InP and In/sub x/Ga/sub 1-x/P. Nonexponential photocapacitance transient is observed in the In/sub x/Ga/sub 1-x/P:Fe for the alloying effects.

Current hoisting technologies employed on South African gold mines is limited in terms of depth. A long stator, short secondary linear synchronous motor is suggested as an alternative in transporting men, material and ore, in order to access reefs in excess of 3000 m.

A deep level investigation has been performed on InAlAs/n/sup +/-InGaAs metal-insulator doped-channel FETs. Two deep levels located in the InAlAs buffer layer have been measured: (i) a hole-like trap, reported for the first time, and (ii) an electron trap, previously identified in the literature. The electron trap was linked to the kink effect. Trap concentrations are low: a maximum measured value of 2/spl times/10/sup 15/ cm/sup -3/. This value is about one order of magnitude lower than that usually measured in GaAs buffer layers for similar gate-length devices. >

Deep levels in undoped semi-insulating (SI) GaAs and Fe-doped SI InP investigated by photoinduced transient spectroscopy (PITS). It is demonstrated that the resolution of this method can be improved by direct computer fitting of digitally recorded photocurrent decays.

Field emission from polycrystalline diamond films is theoretically studied. Defects in the polycrystalline diamond are described as the defects of donor-type with a deep level within the band gap. The results show that field emission current from the conduction band and surface states may be ignored. Field emission from the p-type diamond is due to either a high surface field or negative electron affinity.

The kink effect in InAlAs/InP HFETs was examined in temperature and frequency dependent measurements. A slow states mechanism is found to be probably responsible for the increase of the drain-source conductance related to the kink effect. A deep-level with activation energy of 0.53 eV was deduced from drain conductance dispersion measurements. This level, with a slow emission rate at room temperature, seems to be associated with the kink effect.

This paper provides an investigation on the effects of deep level traps on the large-signal I-V characteristics of GaAs MESFETs by means of measurements and physics-based device simulations; results give clear indications that pulsed I-V measurements are sufficient in order to characterize large-signal AC device operation and provide a good physical basis for circuit-level large signal MESFET models.

Different Fe implantation schemes in n-doped InP have been used in order to create semi-insulating layers with the desired characteristics. The electrical properties of these structures have been investigated by means of current-voltage measurements and deep level analyses; compensation of n-doping up to 1019 cm-3 has been verified. Electroluminescence emission has also been obtained from the compensated samples with the highest substrate doping concentration up to the temperature of 260 K.

Summary form only given. One of the most convenient methods of the basic characterisation of semiconductors is Hall effect measurement by van der Pauw's geometry. As a "by-product" the symmetry factor and a function of the symmetry factor is calculated. In this work we wish to demonstrate that this factor can indicate quite important properties of the sample. Though these properties are connected with inhomogeneities, deep levels can be observed by the temperature dependence of the symmetry factor. Both bulk InP and InP layers on semi-insulating substrates have been studied.

The modeling of low-frequency dispersive effects due to surface state densities, deep level traps and thermal phenomena plays an important role in the large-signal performance prediction of III-V FET' s. This paper describes an empirical modeling approach to accurately predict deviations between static and dynamic drain current characteristics caused by dispersive effects in III-V devices operating at microwave frequencies. It is based on reasonable assumptions and can easily be embedded in nonlinear FET models to be used in Harmonic-Balance tools for circuit analysis and design. Experimental and simulated results, for HEMT's and GaAs MESFET's of different manufacturers, that confirm the validity of the new approach, are presented and discussed together with the characterization procedures required. © 1995 IEEE.