Interface recombination velocity and diffusion constant in HI-LO and P+/N GaAs junctions measured by a microwave technique

A noninvasive microwave technique was used to determine the recombination velocity at the n/n⁺ interface in GaAs grown by organometallic vapor-phase epitaxy. This recombination velocity was measured as a function of the n⁺-doping level and for a choice of dopants (sulfur and silicon) used for the n⁺-region. It is reported that the silicon-doped n/n⁺ interface is superior to the sulfur-doped n/n⁺ interface. Lower dark currents can be obtained for short base diodes with low interface recombination velocity. With long-lifetime material, there is considerable decrease in the dark current because of the resulting increased diffusion length. This technique was also used with p⁺-n junctions to obtain information about the diffusion constant in the n-region. This work is of special interest for high-efficiency solar cell applications.