Effect of post-growth annealing on the recombination centers in C-doped p+-GaAs/n-AlGaAs heterojunctions

Abstract
Recombination current in carbon‐doped p+‐GaAs/n‐AlGaAs junction diodes can be reduced by post‐growth annealing of the epilayers at 600 and 700 °C but not at 500 °C. The reduction of recombination current at 600 °C under the face‐to‐face or SiO2 capped condition is by far larger than that under high‐AsH3 flow, i.e., arsenic overpressure condition. The reduction can be primarily attributed to the reduction in the 0.55‐eV deep levels of recombination centers, which may be an oxygen related complex level with As atoms. The reduction of recombination current at 600 °C is a little smaller when cooling after annealing proceeds slowly, which may be mainly due to around 0.5 eV levels being created during slow cooling. Degradation in the carrier and dopant profiles near junction is not detected even after 700 °C annealing. Annealing at temperatures of 600 °C or higher followed by fast cooling without arsenic overpressure ambient is thus promising for the reduction of recombination centers.