Preparation and Properties of Solution-Grown Epitaxial p—n Junctions in GaP

Abstract

The technique of epitaxial growth from solution has been applied to GaP. Single‐crystalline overgrowths up to 80 μ thick on (111)‐oriented substrate crystals were obtained by the slow cooling of GaP‐saturated Ga solutions. n‐type overgrowths (Te‐doped) on p‐type substrates (Zn, O‐double doped) gave planar p—n junctions free of gross defects. The I—V characteristics of these diodes show an exponential behavior of the form I=I₀ exp (eV/βkT). Values for β were mostly between 1.5 and 1.8 at 300°K. At low currents, the I—V characteristics are interpreted by tunneling. The junctions emitted red light at 300°K in a broad band with the peak at about 1.77 eV (7000 Å). The emission intensity varies with I² at low currents, changes to a linear dependence at intermediate currents, and is sublinear at high currents. The external differential quantum efficiency was measured to be as high as 7.5×10⁻³. The temperature dependence of the emission intensity and the efficiency were measured and are discussed.