20 Result(s)
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Article
P. Stradins
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Article
Optical Absorption in Co-Deposited Mixed-Phase Hydrogenated Amorphous/Nanocrystalline Silicon Thin Films
The conductivity of amorphous/nanocrystalline hydrogenated silicon thin films (a/nc-Si:H) deposited in a dual chamber co-deposition system exhibits a non-monotonic dependence on the nanocrystal concentration. ...
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Time-Resolved Switching Studies in a-Si:H and Related Films
Switching in a-Si:H and a-Si:HNx layers is investigated by pulse current transient and Auger scanning microspectroscopy measurements. Switching in a-Si:H with Ag and Cr contacts exhibits 2 different regimes depen...
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Room Temperature Recovery of Light Induced Changes in Amorphous Silicon Solar Cells
We have observed the recovery of the performance of amorphous silicon (a-Si:H) based solar cell (especially the fill factor) at temperatures between 25°C and 170°C after ∼600 hours of light soaking under 1 sun...
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Crystallization of thin-film Si monitored in real time by in-situ spectroscopic techniques
We have developed optical techniques for real-time, in-situ monitoring of crystallization and epitaxial growth of silicon. Real-time spectroscopic ellipsometry is used for evaluating epitaxial growth during ho...
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Sub-micron Optoelectronic Properties of Polycrystalline Solar Cell Materials
Generation, transport and collection of carriers in polycrystalline (PX) solar cells and their constituent materials are poorly understood, and significantly different than in their single-crystal counterparts...
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Tritium Induced Defects in Amorphous Silicon
We report the growth of tritium induced defects in tritium doped hydrogenated amorphous silicon (a-Si:H.T) as measured by electron spin resonance (ESR) and photothermal deflection spectroscopy (PDS). The measu...
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Investigation of Light-Induced Defect Depth Profile in Hydrogenated Amorphous Silicon Films
We report direct measurement of depth profile of light induced defects (LIDs) in hydrogenated amorphous silicon (a-Si:H) films. These depth profiles were measured by ESR measurements combined with layer-by-lay...
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Light-Induced Degradation Effects in a-Si:H Observed by Raman Scattering Measurements
We have attempted to observe changes in the Raman scattering spectrum of a-Si:H due to light exposure. We do not find any detectable shift of the position or change in the width of the TO phonon peak. We find,...
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Change in The Spectral Shape of the Subgap Absorption in a-SI:H by Photodegradation at 4.2K and its Relation to the Mobility-Lifetime Product
We have observed a pronounced change in the shape of subgap absorption spectrum 6h(h7p) of a-Si:H due to photodegradation at T=4.2K, in contrast to light exposure at T=300K. During the 4.2K exposure, 6h(h7p) a...
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Article
Space Charge Memory Effect in a-Si:H at low Temperatures
Space charges build up near one or both electrodes of a photoconductor unless the thermoionic current balances the photocurrent. Space charges built up also when a voltage U is applied at low T to a semiconduc...
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Article
Photoinduced Reversible Conductivity and Photoconductivity Changes in Transparent Amorphous and Micro-Crystalline In2O3-x FILMS
The dark conductivity σ of poorly conducting In2O3-x films can be enhanced by orders of magnitude by blue or UV light exposure at any temperature between 4.2K and 300K. The resulting high σ state of amorphous fil...
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Transient Photoconductivity of a-Si:H at Low Temperatures Induced by Bandgap Light
The rise and decay of the photoconductivity σp of intrinsic and strongly p-type hydrogenated amorphous silicon (a-Si:H) samples was studied as a function of photocarrier generation rate G between 4.2K and 300K. I...
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Photoconductivity of a-Si:H as a Function of Do**, Temperature and Photocarrier Generation Rates Between 1013 and 1028cm−3s−1
The steady state photoconductivity σp of n-type, p-type and intrinsic a-Si:H has been studied up to photocarrier generation rates of G=5×1027cm−3s−1. In the 20ppm B2H6/SiH4 p-type sample photoconduction switches ...
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Article
Temperature Dependence of the Photoconductivity and the Near Absence of Light-Induced Defects in a-SixGe1-x:H
The photoconductivities σp of glow discharge deposited a-Ge:H and amorphous Si-Ge alloys prepared in different laboratories were measured between 4.2K and 300K and compared with σp(T) of intrinsic and compensated...
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Article
Comparison of Experiment and Theory of the Photoconductivity of a-Si:H up to a Generation Rate of 1028cm−3s−1
We have studied the dependence of the photoconductivity σp on photocarrier generation rate G in intrinsic a-Si:H at 300K between G=1012cm−3s−1 and 1028cm−3s−1. Below a certain value Go, we find σo=AGγ with γ=0.9±...
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Article
Light-Induced Degradation of a-Si:H - A Comparison of Short-Laser-Pulse and Steady Light Degradation
An undoped and a compensated a-Si:H sample have been degraded by 17–34 ns laser pulses and by steady light (CW) at 78K and 300K. The light-induced defect concentration N is monitored by the increase in subgap ...
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Article
The Limitations of the Constant Photocurrent Method for Determining Subgap Absorption
The subgap absorption αcpm measured by the constant photocurrent method (CPM) was studied between 4.2K and 300K for different do**s and defect concentrations N in hydrogenated amorphous silicon (a-Si:H). We fou...
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Article
Transient Infrared Stimulated Photoconductivity in a-SI:H at Low Temperatures
Dual beam photoconductivity with bandgap primary light and hv = 0.4- 0.6eV infrared light steps was measured with Ims time resolution in hydrogenated amorphous silicon (a-Si:H) at 4.2K. The results can be desc...
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Article
The Growth, Steady State and Decay of the Photocarrier Population at low Temperatures
We used the transient infrared photoconductivity to measure the rise and fall of the non-equilibrium photocarrier concentration n at helium temperatures and the conditions for recombination. The growth rate of...
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Evidence for Different Kinds of Dangling Bond Defects in a-Si:H
Comparing the photoconductivity σp of undoped samples with different native defect concentrations we find that light-induced metastable defects decrease the electron lifetime more strongly than the native defects...
