Photoinduced Expansion in Hydrogenated Amorphous Silicon

1999 ◽  
Vol 557 ◽  
Author(s):  
S. Nonomura ◽  
T. Gotoh ◽  
M. Nishio ◽  
T. Sakamoto ◽  
M Kondo ◽  
...  
Keyword(s):  
Time Dependence ◽  
Amorphous Silicon ◽  
Volume Change ◽  
Chalcogenide Glasses ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Structural Aspect ◽  
Photothermal Effect ◽  
Preparation Conditions ◽  
Hydrogenated Amorphous

AbstractThe structural aspect of photodegradation effect in hydrogenated amorphous silicon has been investigated by the use of the simple and sensitive detection technique, the laser optical-lever bending method, for a small expansion or extraction in thin films. The volume change induced by the thermal expansion due to the photothermal effect and the residual expansion was observed in hydrogenated amorphous silicon prepared by PECVD. The latter residual expansion was persistent after light soaking and was recovered by thermal annealing at 200°C.The time dependence of the volume expansion with light soaking shows the same time dependence of photoinduced defect density. The photoinduced volume changes normalized by the initial volume are the order of 10-5~10-5, which values are two orders smaller than chalcogenide glasses such as a-As2S3. The normalized volume change of a-Si:H with the different sample preparation conditions of PECVD such as the hydrogen dilution ratio r (r = SiH4/H2) and substrate temperature is shown. Also it is demonstrated that the photoinduced expansion is observed in hydrogenated amorphous silicon prepared by photo CVD and hot-wire CVD methods. The spatial extent related to a photoinduced defect creation in a-Si:H is estimated.

Pulsed-Light-Induced Metastable Defect Creation in Hydrogenated Amorphous Silicon

1995 ◽  
Vol 377 ◽  
Author(s):  
Jong-Hwan Yoon ◽  
H. L. Kim
Keyword(s):  
Time Dependence ◽  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Pulsed Light ◽  
Illumination Time ◽  
Defect Creation ◽  
Annealing Rate ◽  
Hydrogenated Amorphous ◽  
Metastable Defect

ABSTRACTWe report the results of a study of metastable defect creation by pulsed light soaking in undoped hydrogenated amorphous silicon (a-Si:H). An illumination time dependence of the defect density, a saturated defect density, and light-induced annealing under pulsed laser light have been studied. Measurements show approximately a t1/2 time-dependence of the defect creation, which is independent of light intensity. It is observed that the saturation value of the defect density is about one order of magnitude higher than by cw illumination in device quality films. It has been suggested that these results would be due to the difference in the light-induced defect annealing rate between cw and pulsed lights, in which it is found that the light-induced annealing rate by pulsed light is lower than by cw light.

scholarly journals Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
F. X. Abomo Abega ◽  
A. Teyou Ngoupo ◽  
J. M. B. Ndjaka
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Buffer Layer ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Theoretical Work ◽  
Silicon Based ◽  
The Impact ◽  
Hydrogenated Amorphous

Numerical modelling is used to confirm experimental and theoretical work. The aim of this work is to present how to simulate ultrathin hydrogenated amorphous silicon- (a-Si:H-) based solar cells with a ITO BRL in their architectures. The results obtained in this study come from SCAPS-1D software. In the first step, the comparison between the J-V characteristics of simulation and experiment of the ultrathin a-Si:H-based solar cell is in agreement. Secondly, to explore the impact of certain properties of the solar cell, investigations focus on the study of the influence of the intrinsic layer and the buffer layer/absorber interface on the electrical parameters ( J SC , V OC , FF, and η ). The increase of the intrinsic layer thickness improves performance, while the bulk defect density of the intrinsic layer and the surface defect density of the buffer layer/ i -(a-Si:H) interface, respectively, in the ranges [109 cm-3, 1015 cm-3] and [1010 cm-2, 5 × 10 13  cm-2], do not affect the performance of the ultrathin a-Si:H-based solar cell. Analysis also shows that with approximately 1 μm thickness of the intrinsic layer, the optimum conversion efficiency is 12.71% ( J SC = 18.95   mA · c m − 2 , V OC = 0.973   V , and FF = 68.95 % ). This work presents a contribution to improving the performance of a-Si-based solar cells.

Reduction of the Defect Density in a-Si:H Deposited at ≤250°C

1993 ◽  
Vol 297 ◽  
Author(s):  
Hitoshi Nishio ◽  
Gautam Ganguly ◽  
Akihisa Matsuda
Keyword(s):  
Diffusion Coefficient ◽  
Amorphous Silicon ◽  
Surface Diffusion ◽  
Film Growth ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Device Fabrication ◽  
Surface Diffusion Coefficient ◽  
Hydrogenated Amorphous ◽  
Substrate Temperatures

We present a method to reduce the defect density in hydrogenated amorphous silicon (a-Si:H) deposited at low substrate temperatures similar to those used for device fabrication . Film-growth precursors are energized by a heated mesh to enhance their surface diffusion coefficient and this enables them to saturate more surface dangling bonds.

Improved Light Soaking Stability of R.F. Sputter Deposited Amorphous Silicon

1991 ◽  
Vol 219 ◽  
Author(s):  
A. Wynveen ◽  
J. Fan ◽  
J. Kakalios ◽  
J. Shinar
Keyword(s):  
Amorphous Silicon ◽  
Hydrogen Content ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Dark Conductivity ◽  
Initial Defect ◽  
Optical Gap ◽  
Sputter Deposited ◽  
Staebler Wronski Effect ◽  
Hydrogenated Amorphous

ABSTRACTStudies of r.f. sputter deposited hydrogenated amorphous silicon (a-Si:H) find that the light induced decrease in the dark conductivity and photoconductivity (the Staebler-Wronski effect) is reduced when the r.f. power used during deposition is increased. The slower Staebler-Wronski effect is not due to an increase in the initial defect density in the high r.f. power samples, but may result from either the lower hydrogen content or the smaller optical gap found in these films.

Effect of Deposition-Induced Annealable Defects on Light-Induced Defect Generation in a-Si:H

1993 ◽  
Vol 297 ◽  
Author(s):  
Jong-Hwan Yoon
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Generation Rate ◽  
Defect Generation ◽  
Saturated State ◽  
Microscopic Models ◽  
Hydrogenated Amorphous ◽  
Substrate Temperatures

In this paper we present a method to determine the annealable defect density(ΔNann) present in hydrogenated amorphous silicon(a-Si:H). The effects of the annealable defects on the light-induced defect generation rate, saturated defect density (Nsat) and the change of defect density in the light-induced saturated state(ΔNsat) have been studied. Annealable defect density was varied by depositing samples at various substrate temperatures or by post-growth anneals of samples grown at low substrate temperatures. It is found that the generation rate, N satand ΔNsat are well correlated with ΔNann. In particular, the ΔNsat is found to follow a relation ΔNsat ≈ ΔNann. These results suggest that defect-related microscopic models are appropriate for light-induced metastability.

scholarly journals Integration of Expanding Thermal Plasma deposited Hydrogenated Amorphous Silicon in Solar Cells

2002 ◽  
Vol 715 ◽  
Author(s):  
B.A. Korevaar ◽  
C. Smit ◽  
A.M.H.N. Petit ◽  
R.A.C.M.M. van Swaaij ◽  
M.C.M. van de Sanden
Keyword(s):  
Amorphous Silicon ◽  
Buffer Layer ◽  
Thermal Plasma ◽  
Growth Rates ◽  
Fill Factor ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Temperature Limit ◽  
Cell Efficiency ◽  
Hydrogenated Amorphous

AbstractA cascaded arc expanding thermal plasma is used to deposit intrinsic hydrogenated amorphous silicon at growth rates between 0.2 and 3 nm/s. Incorporation into a single junction p-i-n solar cell resulted in an initial efficiency of 6.7%, whereas all the optical and initial electrical properties of the individual layers are comparable with RF-PECVD deposited films. In this cell the intrinsic layer was deposited at 0.85 nm/s and at a deposition temperature of 250°C, which is the temperature limit for growing the p-i-n sequence. The cell efficiency is limited by the fill factor and using a buffer layer at the p-i interface deposited with RF-PECVD at low growth rate can increase this. The increase in fill factor is a result of a lower initial defect density near the p-i interface then obtained with the expanding thermal plasma, resulting in better charge carrier collection. To use larger growth rates, while maintaining the material properties, higher deposition temperatures are required. Higher deposition temperatures result in a smaller optical bandgap for the intrinsic layer and deterioration of the p-type layer, resulting in a lower opencircuit voltage. First results on applying a buffer layer will also be presented.

A Junction Field Effect Transistor Based on Hydrogenated Amorphous Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
D. Caputo ◽  
G. de Cesare ◽  
A. Nascetti ◽  
V. Kellezi ◽  
F. Palma
Keyword(s):  
Amorphous Silicon ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Gate Electrode ◽  
Linear Behavior ◽  
First Results ◽  
Effect Transistor ◽  
Hydrogenated Amorphous

ABSTRACTAn hydrogenated amorphous silicon junction field effect transistor suitable for analog and digital applications is presented. The device is constituted by a p+ - i - n− junction, with the drain and source contacts patterned on the n-doped layer and the gate electrode patterned on the p+ doped layer. As in the crystalline case, the device is a voltage-controlled resistor, and its drain-source resistance can be varied, with a voltage applied to the gate electrode, by modulating the width of the depletion layer extending into the n-type channel.The doping value of this layer has been chosen as a trade-off between high value of channel conductivity and a relatively low defect density in the material. The manufactured device, with W/L=5000/200 μm, shows the typical current-voltage curves of a JFET. In particular, at low VDS, the current presents the linear behavior of the triode zone, where the JFET operates as a linear resistance whose value is controlled by the gate voltage. At higher VDS the JFET works in the pinch-off region as a dependent current generator.First results are very encouraging, since we have achieved transconductance values of 10−6 V/A, which are comparable to those of state of the art TFT.

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