Electrical and optical properties of heavily doped Mg- and Te-GaAs grown by liquid-phase epitaxy

Abstract

GaAs epitaxial layers doped with Mg and Te were grown on (100) GaAs substrates by liquid-phase epitaxy with a 6°C supersaturation temperature. Room-temperature carrier concentrations up to 2 × 10 19 cm −3 for p-type and 2.6 × 10 19 cm −3 for n-type dopants were obtained reproducibly. Carrier mobilities at 77 K in both n- and p-type layers showed a sharp drop at concentrations higher than 2 × 10 19 cm −3. The full width at half maximum value and the relative intensity of the photoluminescent spectrum increased and decreased, respectively, with carrier concentrations for both Mg- and Te-doped layers, and showed abrupt slope variations near a carrier concentration of 1 × 10 19 cm −3. In Mg-doped GaAs layers, the peak wavelength of photoluminescence spectra increased with hole concentration due to band-gap shrinkage. On the other hand, the photoluminescence peak wavelength decreased with electron concentration due to a Burstein-Moss shift and to band-tailing effects in the Te-doped GaAs layers.