GaAs metal-insulator-semiconductor solar cells with a physically deposited Bi2O3 interfacial layer have been investigated. The deposition techniques used in the study were electron beam and boat thermal evaporation. The cells fabricated with interfacial layers of Bi2O3 showed a substantial improvement in open-circuit voltage over cells made without the physically deposited oxide layer. An etch has been used which yields an irregular ’’textured’’ surface. Cells employing this surface had a higher short-circuit current than those made with smooth, polished surfaces. The open-circuit voltages of these textured cells were lower than those with smooth surfaces. Calculations of the dependence of open-circuit voltage on pinhole density are in agreement with these results since a rough surface has a greater probability of pinholes.

Electron and chemical kinetics in methane rf glowdischarge deposition plasmasElectrical characterization of rf glow discharges using an operating impedance bridge Presented are the results of a systematic study of the effects of reactor pressure and rf power level on the electrical and chemical characteristics of a-C:H films prepared by glow discharge. Electrical resistivity has been found to increase rapidly with decreasing reactor pressure. This increase in electrical resistivity corresponded to an increase in the sp3 bonding content of the film. This composition change has been attributed to increased ion bombardment energy and greater time for adatom surface migration. Electrical resistivity decreased with rf power level. The sp2 bonding content of the film decreased while the sp3 bonding content increased with rf power level. The resistivity change and corresponding composition change could not be explained with the present model.

The electrical resistivity and N content of a-SiN:H films can be controlled by varying the reactor pressure. This appears to be a result of the increased dissociation of the ammonia feed gas by the change in the electron energy spectrum. The effect of ion bombardment of the substrate surface does not result in observable changes in film quality.

The electron trapping phenomenon in a-SiN:H films deposited by radio frequency (rf) glow discharge has been studied as a function of rf power and gas feed ratio. The chemical composition of the films was determined with Fourier transform infrared spectroscopy. The nitrogen content of the films increased with rf power level if the feed ratio of silane to ammonia was sufficient, 1:10. A gas ratio of 1:5 lacked sufficient ammonia fraction to yield nitrogen rich films despite an increase in rf power level. The electrical resistivity increased and in general electron trapping decreased with increasing nitrogen content in the a-SiN:H films. There is weak experimental evidence that an electron trapping minimum is obtained at a film composition similar to stoichiometric silicon nitride. The measured coordination number of 2.4 for films at this stoichiometric ratio corresponded to the optimum coordination number for a random covalent network. This conceivably should yield the lowest trap density material. At this time, however, it is safer to conclude that electron trapping decreases with increasing nitrogen content in the material.

The alloy formation on MIS solar cell metal surfaces due to the drive-out diffusion have been studied here. Au and Ag were used as metal electrodes, SnO2 as an interfacial layer, and GaAs as a substrate. These microscopic reactions at the interface and at the front metal surface are related to the performance and the stability of the GaAs, MS, and MIS solar cells.