Vapor-phase-epitaxial growth of n-AlAs/p-GaAs solar cells

Abstract

Chloride-transport vapor-phase-growth of n-AlAs on p-GaAs single crystal substrates has been carried out in all-alumina reactor to yield high-performance heterostructure solar cells. The same technique and conditions permit growth of AlAs layers on polycrystalline films of GaAs on graphite substrates. The latter material appears promising for less expensive, lower performance cells but is presently not fully developed with regard to compatible contacting technology. Both single crystal and polycrystal AlAs layers are adequately stable to permit several hours of room-ambient handling for device processing and evaluation but must be stored in a dry environment or encapsulated to prevent reaction with water vapor over longer periods. The vapor phase growth method is economically advantageous and readily scaled to the hogh production rates which will be necessary if eventual manufacture for a terrestrial solar electric energy facility is to be seriously considered.