Amorphous thin films for solar-cell applications. Technical progress report, 11 October 1980 to 15 January 1981

Progress has been ahead of planned expectations in three instances: (a) achievement of 4 mA/cm/sup 2/, short circuit current density in a MIS structure solar cell under AM1 illumination; (b) fabrication of large area (4 cm/sup 2/) MIS cells with external J/sub sc/ > 3 mA/cm/sup 2/; and (c) deposition of p/sup +/ layers by B/sub 2/H/sub 6/ gas phase doping. A program status table is included. Reproducible n layers are now routinely deposited by sputtering in Ar, H/sub 2/, and PH/sub 3/ gases. The major remaining obstacle to the goal of a 3.5% cell is the deposition of a quality i-layer. Although information deduced from infrared absorption and Raman data indicates that most of the hydrogen is bonded in the SiH configuration, the photoconductivity of the intrinsic material requires marked improvement. Two forms of magnetron sputtering, planar and cylindrical, are being exploited. The planar deposition system has the advantage that experimental costs are low; the cylindrical system is easily scalable to large product throughput. Schematic illustrations of the two systems and descriptions of apparatus modifications incorporated are included.