ELECTRICAL AND OPTICAL PROPERTIES OF N-TYPE SI-COMPENSATED GAAS PREPARED BY LIQUID-PHASE EPITAXY

The radiative processes in Si-compensated, n-type GaAs prepared by liquid-phase epitaxy have been studied by photoluminescence between 300°and 4.2°K. The data are consistent with the previous hypothesis of the formation under certain growth conditions of two types of acceptor levels by Si in GaAs (in addition to the shallow donor level) with ionization energies of ∼0.03 and ∼0.1 eV. Three basic radiative processes dominate at various temperatures: (a) Band-to-band recombination at 300°K, (b) conduction band (or possibly conduction-band tail states) to shallow acceptor transitions at 4.2°K, and (c) conduction band to the deeper acceptor transitions at 77°K. The half-width of the third emission band and its peak position depends on the Si and free-carrier densities. The degree of compensation of these materials is a function of the substrate orientation. Of the three planes investigated, (100), (111)-Ga, and (111)-As, growth on the (111)-As face results in the lowest degree of compensation. The present study shows that n-type material with mobilities in excess of 1000 cm2/V·sec and electron concentration in the 2-4×1018 cm-3 range can be prepared by growth at 1060°C with the advantage over Te- or Se-doped GaAs that the formation of precipitates of Ga2Se3 or Ga2Te3 is eliminated. Such precipitates were previously shown to seriously degrade the radiative efficiency and hence the performance of injection lasers and spontaneous emitters. © 1969 The American Institute of Physics.