Defect Properties of Cathode Deposited Glow Discharge Amorphous Silicon Germanium Alloys

1995 ◽  
Vol 377 ◽  
Author(s):  
Fan Zhong ◽  
Chih-Chiang Chen ◽  
J. David Cohen ◽  
Paul Wickboldt ◽  
William Paul
Keyword(s):  
Glow Discharge ◽  
Silicon Germanium ◽  
Defect Formation ◽  
Optical Spectra ◽  
Drive Level ◽  
Formation Model ◽  
Energy Distributions ◽  
Amorphous Silicon Germanium ◽  
Discharge Method ◽  
Defect Densities

ABSTRACTWe have characterized the deep defect densities and their energy distributions for a series of a-Si1-xGex:H alloys with large Ge content (0.57< × < 1.00) prepared by the cathode deposited glow discharge method. Our results indicate markedly superior properties for these samples. A small Urbach tail slope (about 45meV) was found for all samples in this alloy range. The defect densities were either obtained directly from the drive-level capacitance profiling or deduced from the sub-band-gap optical spectra. Both are substantially lower than the trend line determined from previous studies of a-Si1-xGex:H samples produced by conventional glow discharge and by Photo-CVD methods. However, the relation between the total defect densities and the optical spectra in the cathodic samples obeys the same defect formation model that has been used to successfully predict the defect densities in other types of a-Si1-xGex:H material.

The Electronic Structure, Metastability and Transport Properties of Optimized Amorphous Silicon-Germanium Alloys

1998 ◽  
Vol 507 ◽  
Author(s):  
Chih-Chiang Chen ◽  
Yoram Lubianiker ◽  
J. David Cohen ◽  
Jeffrey C. Yang ◽  
Subhendu Guha ◽  
...  
Keyword(s):  
Transport Properties ◽  
Silicon Germanium ◽  
Defect Formation ◽  
Harvard University ◽  
Defect Formation Energy ◽  
Solar Systems ◽  
Before And After ◽  
Amorphous Silicon Germanium ◽  
Defect Densities ◽  
Comprehensive Study

ABSTRACTWe have carried out a comprehensive study of the electronic properties of two series of optimized a-Si1−xGex:H alloys fabricated at United Solar Systems Corporation (“Uni-Solar”) and Harvard University, encompassing the composition range 0.2 ≤ × ≤ 1.0. Both series of samples exhibit deep defect densities that obey quite accurately the spontaneous bond-breaking model proposed by M. Stutzmann which, by considering how the defect formation energy varies with the position of Fermi energy, we have been able to extend to doped samples.We have also extended our studies to include measurements of ambipolar diffusion lengths and the effects of light-induced degradation, and thus have been able to demonstrate a direct relation between these transport properties and the measured defect levels before and after degradation.

Properties of amorphous silicon-germanium films and devices deposited at higher growth rates

2002 ◽  
Vol 715 ◽  
Author(s):  
Yong Liu ◽  
Vikram L. Dalal
Keyword(s):  
Amorphous Silicon ◽  
Growth Rates ◽  
Silicon Germanium ◽  
Urbach Energy ◽  
Dark Conductivity ◽  
Film Properties ◽  
Ecr Plasma ◽  
Device Properties ◽  
Amorphous Silicon Germanium ◽  
Defect Densities

AbstractWe report on the growth and properties of amorphous Silicon-Germanium [a–(Si,Ge):H] films and devices fabricated at growth rates of ∼ 5 Å/sec using a remote ECR plasma growth process. The films and devices were made using mixtures of germane and silane along with dilution with hydrogen and helium. The addition of He to the gas mixture significantly increased the growth rates. It was found that hydrogen was always necessary in order to achieve the best film and device properties. Films and devices were made across the entire bandgap range, from a-Si to a-Ge. High ratios of photo/dark conductivity and low values of Urbach energy ( > 50 meV) indicate good film properties. The defect densities were measured using space charge limited current techniques. The defect densities were in the range of 1-2 x 10 16/cm 3 –eV, about 5 times higher than for a-Si:H. Electron mobility-lifetime products were measured and found to be in the range of 2-4 x 10-7 cm2/V, even for low gap materials (1.35 eV). Single and graded gap devices were fabricated in these materials. Device fill factors of ∼ 70% were obtained in graded gap devices.

Optoelectronic Properties of Amorphous SiGec Alloys

1992 ◽  
Vol 258 ◽  
Author(s):  
J. Kolodzey ◽  
R. Schwarz ◽  
F. Wang ◽  
T. Muschik ◽  
J. Krajewski ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Plasma Deposition ◽  
Optical Gap ◽  
Random Alloy ◽  
Amorphous Si ◽  
Silicon Germanium Carbon ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous ◽  
Average Bond ◽  
Defect Densities

ABSTRACTWe describe the optoelectronic characteristics of hydrogenated amorphous silicon germanium carbon (a.Si1-x-yGexCy:H) alloys prepared by plasma deposition from SiH4/GeH4/CH4/H2 gas mixtures. a-Si1-x-yGexCy:H is a homogeneous random alloy having a variable optical gap depending on composition, with properties similar to those of amorphous Si-Ge alloys of the same optical gap but with improved thermal stability. Calculations show that if the ratio of Ge/C atomic fractions is 8.2, the average bond length matches that of unalloyed amorphous a-Si:H with the possibility of reduced defect densities at heterointerfaces. After light-soaking with high intensity white light, a sample having a 1.3 eV optical gap exhibited no Staebler-Wronski change in its properties.

Light-Induced Degradation of Amorphous Silicon-Germanium Alloy Solar Cells Deposited at High Rates

1996 ◽  
Vol 420 ◽  
Author(s):  
S. Sugiyama ◽  
X. Xu ◽  
J. Yang ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Ion Bombardment ◽  
Ir Absorption ◽  
Film Properties ◽  
Deposition Rates ◽  
Rf Glow Discharge ◽  
Amorphous Silicon Germanium

AbstractWe have studied the light-induced degradation of amorphous silicon-germanium (a-SiGe:H) alloy single-junction solar cells with high initial performance deposited at high rates. The intrinsic layers were deposited using microwave (MW) glow-discharge technique at deposition rates between 10 and 40 Å/s. The results show that light-induced degradation of the cells is higher than that of cells deposited at low rates using RF glow-discharge technique, and it does not strongly depend on deposition rates over this range. The total hydrogen content and the ratio of Si-H2, Ge-H, and Ge-H2 to Si-H bonding estimated by infrared (IR) absorption in films are correlated with the cell degradation results. We have also investigated the effect of ionbombardment on film properties. Films with low ion-bombardment are more porous and have higher composition of Si-H2 and Ge-H2 bonding. Appropriate ion-bombardment makes denser structure in a-SiGe:H alloy films deposited at high rates. This improves the cell performance as well.

Infrared Spectroscopy of Deuterated a-Si, Ge:D, F Alloys Prepared by DC Glow Discharge Deposition

1986 ◽  
Vol 70 ◽  
Author(s):  
Y. Okada ◽  
D. Slobodin ◽  
S. F. Chou ◽  
R. Schwarz ◽  
S. Wagner
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Dc Glow Discharge ◽  
Thermochemical Equilibrium ◽  
Amorphous Silicon Germanium ◽  
Glow Discharge Deposition

ABSTRACTDeuterated and fluorinated amorphous silicon-germanium alloys, a-Si, Ge:D, F, were studied by Fourier transform infrared (IR) spectroscopy. No Ge.-F modes are observed. The intensity of the Si-F and Si-F2 modes increases with Ge concentration. So does thae intensity of SiF4 which is trapped as isolated molecules. No DF (IR) or F2 (Raman) is observed. The IR spectra of alloys annealed at 300, 400, 500 and 600° C show that the fluorine in the Si-F and Si-F2 groups and in the SiF4 molecules is in thermochemical equilibrium.

Electronic Properties of RF Glow Discharge Intrinsic Microcrystalline Silicon near the Amorphous Silicon Phase Boundary

2004 ◽  
Vol 808 ◽  
Author(s):  
James J. Gutierrez ◽  
Adam F. Halverson ◽  
Eric D. Tweeten ◽  
J. David Cohen ◽  
Baojie Yan ◽  
...  
Keyword(s):  
Glow Discharge ◽  
Electronic Properties ◽  
Minority Carrier ◽  
Microcrystalline Silicon ◽  
Silicon Phase ◽  
Doping Density ◽  
Rf Glow Discharge ◽  
First Time ◽  
Discharge Method ◽  
Defect Densities

ABSTRACTThe electronic properties of microcrystalline silicon have been characterized for the first time using transient photocapacitance spectroscopy (TPC) and drive-level capacitance profiling (DLCP). These methods were applied to microcrystalline films deposited by the RF glow discharge method at United Solar. The DLCP method allowed the shallow doping density to be profiled and the deep defect densities to be estimated. The TPC spectra were found to reveal that both a microcrystalline as well as an amorphous component are present in these samples. By varying the measurement temperature for these TPC spectra we were also able to directly monitor the degree of minority carrier collection in these films. Significant effects due to light soaking on the TPC spectral properties were also observed.

Electronic Transport and the Density of States Distribution in a-(Si, Ge):H, F Alloys

1986 ◽  
Vol 70 ◽  
Author(s):  
S. Aljishi ◽  
Z E. Smith ◽  
D. Slobodin ◽  
J. Kolodzey ◽  
V. Chu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Density Of States ◽  
Electronic Transport ◽  
Silicon Germanium ◽  
Drift Mobility ◽  
Electronic And Optical Properties ◽  
Reported Data ◽  
Amorphous Silicon Germanium

ABSTRACTThe electronic and optical properties of amorphous silicon-germanium alloys produced by d.c. and r.f. glow discharge are reported. Data on the sub-gap absorption, dark and photo conductivities, drift mobilities and drift mobility-lifetime products are used to propose a density of states model.

Hydrogenated Amorphous Silicon Germanium Alloys Prepared by Triode rf Glow Discharge

1986 ◽  
Vol 25 (Part 2, No. 4) ◽  
pp. L276-L278 ◽  
Author(s):  
Takeshige Ichimura ◽  
Takurou Ihara ◽  
Toshio Hama ◽  
Michio Ohsawa ◽  
Hiroshi Sakai ◽  
...  
Keyword(s):  
Glow Discharge ◽  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Hydrogenated Amorphous Silicon ◽  
Rf Glow Discharge ◽  
Amorphous Silicon Germanium ◽  
Hydrogenated Amorphous ◽  
Silicon Germanium Alloys

Influence of Hydrogen on the Germanium Incorporation in a-Si1-xGex:H for Thin-film Solar Cell Application

2010 ◽  
Vol 1245 ◽  
Author(s):  
Chien-Ming Wang ◽  
Yen-Tang Huang ◽  
Yen Kuo-Hsi ◽  
Hung-Jung Hsu ◽  
Cheng-Hang Hsu ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cell ◽  
Silicon Germanium ◽  
Defect Formation ◽  
Film Growth ◽  
Growth Defect ◽  
Solar Cell Application ◽  
Hydrogen Dilution ◽  
Amorphous Silicon Germanium ◽  
Analytical Tools

AbstractIn this work, we examined the Ge incorporation and the accompanied defect formation during PECVD deposition of hydrogenated amorphous silicon-germanium alloys (a-Si1-xGex:H). In particular, we studied the effect of hydrogen on film growth, defect formation, Ge and Si incorporation efficiencies, and the H-bonding configuration. Our results indicate that hydrogen has a strong effect on improving the a-Si1-xGex:H film quality and the Ge incorporation in a-Si1-xGex:H. With adequate hydrogen dilution, the a-Si1-xGex:H thin-film quality significantly improved. However, excessive hydrogen dilution degraded the film properties. A number of analytical tools were employed, including FTIR, XPS, UV-Visible spectroscopy, photoconductivity, etc. The a-Si1-xGex:H material having 24% Ge content and a bangap of 1.61ev produced the solar cell with a conversion efficiency of 7.07%.

Sign in / Sign up

Export Citation Format

Share Document