Preparation and properties of solution-grown epitaxial p - N junctions in gap

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. © 1966 The American Institute of Physics.