Deep levels and minority carrier lifetime in MOVPE p-type GaAs

Abstract

Deep levels in p-type GaAs have direct impact on the performance of many devices, such as the hetero-junction transistor (HBT). We have studied the influences of dopant elements (Mg or Zn), growth temperature, and doping concentration on the characteristics of the deep levels in p-GaAs via n+-p GaAs homojunctions grown by metalorganic vapor phase epitaxy (MOVPE). Over various growth conditions, four hole traps and an electron trap with activation energies in the range of 0.18-0.79 eV were measured in GaAs: Mg. Only a single hole trap, which is also detected in GaAs: Mg, has been measured in GaAs: Zn. The characteristics of the deep levels presented in GaAs: Mg depend mainly on the doping concentration of Mg. The possible origins of several of these traps have been identified. Overall, the total concentration in the GaAs: Mg decreases rapidly with doping concentration for p>4×1017 cm-3. Upon comparison, the total deep trap concentration in GaAs: Mg is always greater than in GaAs: Zn, indicating that Zn is a preferred p-type dopant for MOVPE GaAs. © 1988.