Fabrication of GaAs tunnel junctions by a rapid thermal diffusion process

A rapid thermal diffusion process for the fabrication of GaAs tunnel junctions, utilizing a doped oxide zinc source and a protective cap layer of phosphosilicate glass, is described in this letter. It is shown that tunnel junctions fabricated by this open tube process are suited for low impedance interconnects in tandem solar cells, and also for tunnel diode field-effect transistor logic applications. The resulting voltage-current characteristics in both silicon and sulfur doped n+ epilayers, and the peak current as a function of effective doping concentration, are also presented. It is shown that diodes made by this process are comparable in electrical properties to those made by molecular beam epitaxy.