Process research on polycrystalline-silicon material (PROPSM). Quarterly report No. 10, April 1, 1983 - June 30, 1983

Technical Report · Sat Jan 01 04:00:00 EST 1983

DOI:https://doi.org/10.2172/5796560· OSTI ID:5796560

Culik, J. S.

The investigation of the performance-limiting mechanisms in large-grain (greater than 1 to 2 mm in diameter) polycrystalline silicon was continued by measuring the illuminated current-voltage (I-V) characteristics of the mini-cell wafer set. Low average values of open-circuit voltage and a great degree of open-circuit voltage and fill-factor scatter were correlated with the presence of inclusions, which was also correlated with significantly greater values of shunt conductance. Therefore, the scatter in the open-circuit voltage, fill-factor and power of solar cells presently fabricated from cast large-grain polycrystalline silicon is due, to some extent, to inclusions, which act as resistive shunts. However, this defect is not intrinsic since a number of polycrystalline wafers shown no indication of excessive shunt conductance or the presence of inclusions. Two processes, gettering and hydrogenation, are being investigated for improving the performance of polycrystalline silicon. Several experiments were performed to evaluate the usefulness of a 1000/sup 0/C back-side damage-gettering heat treatment for removing minority-carrier lifetime-killing impurities. At present, no improvement in minority-carrier lifetime has been observed. The photoconductivity decay time of the polycrystalline silicon wafers was systematically and significantly degraded by longer heat-treatments at 1000/sup 0/C. There appears to be a minority-carrier lifetime-killing mechanism in polycrystalline silicon that is activated by the high temperatures employed in this particular damage-gettering heat treatment. A system for DC plasma hydrogenation of 2 cm x 2 cm samples is being refurbished to investigate grain and subgrain boundary passivation.

• Research Organization: Solarex Corp., Rockville, MD (USA)
• DOE Contract Number: NAS-7-100-955902
• OSTI ID: 5796560
• Report Number(s): DOE/JPL/955902-83/10; ON: DE83016820
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
CHEMICAL REACTIONS
DATA COVARIANCES
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
ELECTRICAL PROPERTIES
EQUIPMENT
FILL FACTORS
GETTERING
HYDROGENATION
PASSIVATION
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
SILICON SOLAR CELLS
SOLAR CELLS
SOLAR EQUIPMENT