Substrate Temperature Dependence of the Optical and Electronic Properties of Glow Discharge Produced a-Ge:H

1989 ◽  
Vol 149 ◽  
Author(s):  
Yuan- Min Li ◽  
Warren A. Turner ◽  
Choochon Lee ◽  
William Paul
Keyword(s):  
Glow Discharge ◽  
Substrate Temperature ◽  
Temperature Dependence ◽  
Electronic Properties ◽  
Dark Conductivity ◽  
Index Of Refraction ◽  
Atmospheric Contamination ◽  
Optical And Electronic Properties ◽  
Substrate Temperatures ◽  
Post Deposition

ABSTRACTGlow discharge a-Ge:H films produced at substrate temperatures (Tδ) between 50°C and 350°C, with and without a top a-Si:H capping layer, have been studied. The uncapped samples produced at Tδ < 250°C suffer severe post-deposition atmospheric contamination, resulting in orders of magnitude of unstable increase in both the photoresponse and dark conductivity. The capped samples, which have very much reduced immediate post-deposition contamination, show only small increases in the efficiency-mobility-lifetime product (ŋμτ) with increasing Tδ. This contrasts with the results of earlier similar studies on uncapped samples, which showed a peak in either the photoconductivity1 or the ratio of photoconductivity to dark conductivity2 for 150°C < Tδ < 2000C. We have also observed a decrease in the bandgap, a narrowing of the band-tails, an increase in the index of refraction, and a reduction of hydrogen content of the films with increasing Tδ.

Intermixing at the CdS/CdTe Interface and its Effect on Device Performance

1996 ◽  
Vol 426 ◽  
Author(s):  
R. G. Dhere ◽  
D. S. Albin ◽  
D. H. Rose ◽  
S. E. Asher ◽  
K. M. Jones ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Substrate Temperature ◽  
Secondary Ion Mass Spectrometry ◽  
Spectral Response ◽  
Device Performance ◽  
Quality Factors ◽  
X Ray Diffraction ◽  
Current Voltage ◽  
Substrate Temperatures ◽  
Post Deposition

AbstractA study of the CdS/CdTe interface was performed on glass/SnO2/CdS/CdTe device structures. CdS layers were deposited by chemical solution growth to a thickness of 80–100 nm, and CdTe was deposited by close-spaced sublimation at substrate temperatures of 500°, 550°, and 600°C. Post-deposition CdCl2 heat treatment was performed at 400°C. Samples were analyzed by optical spectroscopy, secondary ion mass spectrometry (SIMS), spectral response, and current-voltage measurements. SIMS analysis shows that the intermixing of CdS and CdTe is a function of substrate temperature and post-deposition CdCl2 heat treatment. The degree of intermixing increases with increases in substrate temperature and the intensity of CdCl2 heat treatment. Optical analysis and X-Ray diffraction data show that the phases of CdSxTe1-x are also a function of the same parameters. Formation of a Te-rich CdSxTe1-x alloy is favored for films deposited at higher substrate temperatures. Spectral response of the devices is affected by the degree of alloying at the interface. The degree of alloying is indicated by simultaneous changes in long wavelength response (due to the formation of lower bandgap intermixed CdSxTe1-x) and the short wavelength response (due to the change in CdS thickness). Device performance is heavily influenced by alloying at the interface. With optimized intermixing, improvements in Voc, and diode quality factors are observed in the resulting devices.

Measurements of Light-Induced Degradation in A-Si, Ge:H, F Alloys,

1986 ◽  
Vol 70 ◽  
Author(s):  
J. Kolodzey ◽  
S. Aljishi ◽  
Z E. Smith ◽  
V. Chu ◽  
R. Schwarz ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electronic Properties ◽  
Dark Conductivity ◽  
Narrow Gap ◽  
Conductivity Activation Energy ◽  
Optical And Electronic Properties ◽  
Amorphous Si

ABSTRACTThe effects of illumination on the optical and electronic properties of narrow gap hydrogenated and fluorinated amorphous Si-Ge (a-Si1-xGex:H, F) alloys have been evaluated. A series of alloys with optical gaps ranging from 1.30 eV to 1.64 eV has been light soaked at ∼1 sun intensity for 354 hours. Measurements of sub-gap absorption, photo- and dark conductivities and dark conductivity activation energy were made on alloys in the annealed and the light-soaked states. The results indicate that samples with optical gaps ≳ 1.4 eV degrade significantly. The 1.3 eV sample shows no degradation in its optical or electronic properties except for a factor of 5 increase in the dark conductivity.

Influence of Growth Parameters and Annealing on Properties of MBE Grown GaAsSbN SQWs

2005 ◽  
Vol 872 ◽  
Author(s):  
Liangjin Wu ◽  
Shanthi Iyer ◽  
Kalyan Nunna ◽  
Sudhakar Bharatan ◽  
Jia Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Substrate Temperature ◽  
Temperature Dependence ◽  
Growth Parameters ◽  
Blue Shift ◽  
Growth Conditions ◽  
Ex Situ ◽  
Single Quantum Well ◽  
Substrate Temperatures

AbstractIn this paper we report the growth of GaAsSbN/GaAs single quantum well (SQW) heterostructures by molecular beam epitaxy (MBE) and their properties. A systematic study has been carried out to determine the effect of growth conditions, such as the source shutter opening sequence and substrate temperature, on the structural and optical properties of the layers. The substrate temperatures in the range of 450-470 °C were found to be optimal. Simultaneous opening of the source shutters (SS) resulted in N incorporation almost independent of substrate temperature and Sb incorporation higher at lower substrate temperatures.The effects of ex-situ annealing in nitrogen ambient and in-situ annealing under As overpressure on the optical properties of the layers have also been investigated. A significant increase in photoluminescence (PL) intensity with reduced full width at half maxima (FWHM) in conjunction with a blue shift in the emission energy was observed on annealing the samples. In in-situ annealed samples, the PL line shapes were more symmetric and the temperature dependence of the PL peak energy indicated significant decrease in the exciton localization energy as exhibited by a less pronounced “S-shaped curve”. The “inverted S-shaped curve” observed in the temperature dependence of PL FWHM is also discussed. 1.61 μm emission with FWHM of 25 meV at 20K has been obtained in in-situ annealed GaAsSbN/GaAs SQW grown at 470 °C by SS.

Optical and electronic properties of amorphous SiNx:H alloy films

1985 ◽  
Vol 63 (6) ◽  
pp. 846-851 ◽  
Author(s):  
T. V. Herak ◽  
R. D. McLeod ◽  
M. G. Collett ◽  
K. C. Kao ◽  
H. C. Card ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Electronic Properties ◽  
Optical Excitation ◽  
Dark Conductivity ◽  
Dangling Bond ◽  
Alloy Films ◽  
Optical And Electronic Properties ◽  
Rf Glow Discharge ◽  
Gap States ◽  
Induced Changes

The optical and electronic properties of a-SiNx:H alloy films fabricated by rf glow discharge have been measured for 0 ≤ x ≤ 0.6. The material is dispersive over the range of photon energies 0.5 ≤ hv ≤ 3.5 eV. The optical gap is about 1.65 eV and is practically independent of x for 0.1 < x < 0.4, but it increases rapidly with increasing x for 0 < x < 0.1 and x > 0.4. For x > 0.6 the refractive index approaches the value for Si3N4. The dark conductivity, the photoconductivity, and the ratio of the photoconductivity to the dark conductivity are enhanced by nitrogen incorporation when appropriate nitrogen content is used. All the experimental results indicate that the incorporated nitrogen does not act as a dopant, but rather acts as a dangling-bond compensator. Photo-induced changes in both dark conductivity and photoconductivity due to high-intensity optical excitation have been observed. The degree of such changes decreases with increasing nitrogen content. This phenomenon is attributed to the photo-induced change in the microstructure of the films that leads to a change in both the density and the distribution of gap states.

Low Defect Density Microcrystalline-Si Deposited by the Hot Wire Technique

1998 ◽  
Vol 507 ◽  
Author(s):  
A. H. Mahan ◽  
M. Vanecek ◽  
A. Poruba ◽  
V. Vorlicek ◽  
R. S. Crandall ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Defect Density ◽  
Structural Data ◽  
Hot Wire ◽  
Very High Frequency ◽  
Deposition Parameters ◽  
Optical And Electronic Properties ◽  
High Filament ◽  
Si Films ◽  
Substrate Temperatures

ABSTRACTThe optical and electronic properties of a series of microcrystalline silicon (μ-Si) films, deposited by the hot wire (HW) technique, are reported. Preliminary results suggest, using moderate H2 /SiH4 dilution ratios and substrate temperatures (320°C), high filament temperatures, and no H gas purifier, that the subgap absorption for these films, measured using the constant photocurrent (CPM) method, can be as low as that obtained for films deposited by the very high frequency glow discharge (VHF-GD) technique. The film dark conductivities of the HW samples, ranging as low as 2.0 × 10−8 (ohm cm)−1, lend further credance to these low defect values. At the same time, the optical absorption in the region > 1.6 eV is higher than that previously observed for the VHF-GD deposited samples. The present results, discussed in the context of the film microcrystalline fraction, suggest that there is no unique, good quality, low defect density μ-Si material, and that different deposition techniques can be used to successfully deposit device quality gc-Si. We also present optical and structural data for films deposited at lower substrate temperatures and higher deposition rates, and suggest combinations of deposition parameters to be used that may further improve the electronic properties of these films.

Preparation of α-(Si.Ge):H Alloys by D.C. Glow Discharge Deposition

1985 ◽  
Vol 49 ◽  
Author(s):  
D. Slobodin ◽  
S. Aljishi ◽  
R. Schwarz ◽  
S. Wagner
Keyword(s):  
Glow Discharge ◽  
Substrate Temperature ◽  
Dark Conductivity ◽  
Germanium Content ◽  
Alloy Films ◽  
Optical Gap ◽  
Glow Discharge Deposition

AbstractWe report the preparation of α-(Si.Ge):H alloy films by decomposition of SiF4, GeF4, and H2 in a d.c. glow discharge. Germanium is incorporated very efficiently from GeF4. The germanium content and optical gap canbe controlled by varying the GeF4 flow while keeping the SiF4 and H2 flows constant. The films, all prepared at 300 ºC substrate temperature, exhibit high photo- to dark-conductivity ratios for compositions of up to -25% germanium.

Sign in / Sign up

Export Citation Format

Share Document