Investigation of the Electrical and Optical Properties of Organometallic Vapor-Phase Epitaxial Al/sub X/Ga/sub 1-X/As and Al/sub X/Ga/sub 1-X/As/GaAs Interfaces in Solar Cells. Progress Report, 16 December 1981-1 December 1982

摘要

Several fundamental properties in the organometallic vapor phase epitaxial (OMVPE) Al/sub x/Ga/sub 1-x/As alloys have been revealed and interpreted. Dominant electron traps in these alloys have been identified for the first time. A consistent behavior of the deep traps in these materials, where the trap activation energy and capture cross-section show definite trends, have been explained by the lattice relaxation model. The results also throw light on the physico-chemical origin on the origin of a deep trap labeled EL2 in these materials. Low-field mobilities in the alloys have been measured as a function of temperature in alloys with 0 less than or equal to x less than or equal to 0.8. For x less than or equal to 0.3 the mobility values can be interpreted by the known scattering theories. Abnormally high mobilities in alloys with x less than or equal to 0.35 are being observed for the first time and have been interpreted by considering the modulation doping process. This effect has important effects on the performance of cascade solar cell. Photoluminescence data indicate the presence of C, Si, Ge and Cu as the major impurities in OMVPE Al/sub x/Ga/sub 1-x/As. (ERA citation 08:012043)