scholarly journals A Study of Electronic Defects in Hydrogenated Amorphous Silicon Prepared by the Expanding Thermal Plasma Technique

2003 ◽  
Vol 762 ◽  
Author(s):  
Steve Reynolds ◽  
Charlie Main ◽  
Ivica Zrinscak ◽  
Zdravka Aneva ◽  
Diana Nesheva
Keyword(s):  
Amorphous Silicon ◽  
Thermal Plasma ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Band Tail ◽  
Plasma Technique ◽  
Transient Photoconductivity ◽  
Electronic Defects ◽  
Hydrogenated Amorphous ◽  
Deposition Conditions

AbstractThe electronic properties of amorphous silicon films prepared by the expanding thermal plasma technique have been studied using steady-state and transient photoconductivity measurements. It is found that films deposited at a substrate temperature of 400°C have a conduction band tail slope of 29 meV, deep defect density of order 3×1016 cm-3, an Urbach tail slope of 65 meV, defect absorption of 5-10 cm-1, and a mobility-lifetime product of 1.3×10-7 cm2 V-1. Aslight increase in defect density and reduction in mobility-lifetime product is observed on moderate light-soaking. The overall optoelectronic quality is somewhat poorer than commercial PECVD material, but there is scope for improvement as deposition conditions are further optimised.

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.

scholarly journals Material Parameters in a Thick Hydrogenated Amorphous Silicon Detector and their Effect on Signal Collection

1989 ◽  
Vol 149 ◽  
Author(s):  
S. Qureshi ◽  
V. Perez-Mendez ◽  
S. N. Kaplan ◽  
I. Fujieda ◽  
G. Cho
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Detector ◽  
Dangling Bond ◽  
Material Parameters ◽  
Bond Density ◽  
Transient Photoconductivity ◽  
Signal Collection ◽  
Hydrogenated Amorphous

ABSTRACTTransient photoconductivity and ESR measurements were done to relate the ionized dangling bond density and the spin density of thick hydrogenated amorphous silicon (a-Si:H) detectors. We found that only a fraction (∼30–35%) of the total defect density as measured by ESR is ionized when the detector is biased into deep depletion. The measurements on annealed samples also show that this fraction is about 0.3. An explanation based on the shift of the Fermi energy is given. The measurements show that the time dependence of relaxation is a stretched exponential.

Recombination Process in the As-Deposited State of Hydrogenated Amorphous Silicon

1993 ◽  
Vol 297 ◽  
Author(s):  
Jong-Hwan Yoon
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Energy Levels ◽  
Hydrogenated Amorphous Silicon ◽  
Recombination Process ◽  
Defect States ◽  
Deep Defect ◽  
Recombination Centers ◽  
Hydrogenated Amorphous ◽  
Deposition Conditions

Intrinsic deep defect-related recombination process has been studied in a series of undoped hydrogenated amorphous silicon(a-Si:H) films grown under different deposition conditions. Steady-state photoconductivity (σph) was measured as a function of deep defect density Nd, Urbach energy Eu, and dark Fermi energy Ef. It was found that σph strongly depends on these parameters while Ef- stays at the energy levels lower than 0.82 eV below Ec, but it is nearly independent of those while Ef stays at above 0.82 eV. These behaviors were found to be independent of the sample deposition conditions. These results indicates that subgap defect states enclosed by E=0.82 eV and Ef are the dominant recombination centers.

Post-transit Analysis of Transient Photocurrents from High-Deposition-Rate a-Si:H Samples

2003 ◽  
Vol 762 ◽  
Author(s):  
Monica Brinza ◽  
W.M.M. Kessel ◽  
Arno H.M Smets ◽  
M.C.M van de Sanden ◽  
Guy J. Adriaenssens
Keyword(s):  
Amorphous Silicon ◽  
Deposition Rate ◽  
Density Of States ◽  
Thermal Plasma ◽  
Hydrogenated Amorphous Silicon ◽  
High Deposition Rate ◽  
Flight Experiment ◽  
Plasma Technique ◽  
Gap States ◽  
Hydrogenated Amorphous

AbstractAn interpretation of post-transit photocurrents in a time-of-flight experiment in terms of the underlying density of localized gap states in the sample is presented for the case of hydrogenated amorphous silicon cells prepared by the expanding thermal plasma technique. It is pointed out that part of the observed current is not generated by re-emission of trapped photo-generated charge and should, therefore, not be used for density-of-states calculations.

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.

Sign in / Sign up

Export Citation Format

Share Document