Microscopic origins of metastable effects in a-Si:H and deep defect characterization in a-Si,Ge:H alloys. Annual subcontract report, 1 February 1991--31 January 1992
- Oregon Univ., Eugene, OR (United States)
This report describes works to use transient photocapacitance and photocurrent measurements to determine the deep defect distribution and processes in low-band-gap a-Si,Ge:H alloys. Samples for these studies were produced by the photochemical vapor deposition (photo-CVD) growth method and were obtained through a collaboration with researchers at the University of Delaware. This report discusses how a detailed comparison between the photocapacitance and photocurrent spectra can be used to separately examine the majority and minority carrier processes. The results are as follows: (1) The midgap defect densities in the alloy regime near 1.3 eV can be as low as 5 {times} 10{sup 16} cm{sup {minus}3} in such photo-CVD samples. (2) There exists a second defect band roughly 0.4 eV below E{sub c} of a similar magnitude to the midgap defect density that exhibits significant lattice relaxation behavior in its electron trapping dynamics. (3) The hole {mu}{tau} products determined for the lowest defect sample are roughly 5 {times} 10{sup {minus}10} cm{sup 2}/V, comparable with the highest hole {mu}{tau} products reported in sandwich geometry measurements for alloys in this composition range. (4) The hole {mu}{tau} is found to be roughly inversely proportional to the midgap defect density for the samples studied. This is consistent with the fact that the effective minority carrier lifetime for such measurements is limited by the deep state trapping time.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Oregon Univ., Eugene, OR (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-83CH10093
- OSTI ID:
- 10170190
- Report Number(s):
- NREL/TP-451-4938; ON: DE92010588
- Resource Relation:
- Other Information: PBD: Jul 1992
- Country of Publication:
- United States
- Language:
- English
Similar Records
Microscopic Origins of Metastable Effects in a-Si:H and Deep Defect Characterization in a-Si,Ge:H Alloys, Annual Subcontract Report, 1 February 1992 - 31 January 1993
Microscopic Origins of Metastable Effects in a-Si:H and Deep Defect Characterization in a-Si,Ge:H Alloys: Final Subcontract Report, 1 February 1991 - 31 January 1994
Related Subjects
36 MATERIALS SCIENCE
SILICON
CRYSTAL DEFECTS
SOLAR CELLS
SEMICONDUCTOR MATERIALS
PROGRESS REPORT
AMORPHOUS STATE
METASTABLE STATES
SILICON SOLAR CELLS
PHOTOCONDUCTIVITY
CHEMICAL VAPOR DEPOSITION
PHOTOCURRENTS
CAPACITANCE
SEMICONDUCTOR JUNCTIONS
GERMANIUM ALLOYS
140501
360606
360602
PHOTOVOLTAIC CONVERSION
PHYSICAL PROPERTIES
STRUCTURE AND PHASE STUDIES