Radiative electron-hole recombination in a new sawtooth semiconductor superlattice grown by molecular-beam epitaxy

Abstract

A new sawtooth-shaped conduction- and valence-band potential in GaAs is generated by alternating n- and p-type Dirac-δ doping, i.e., by interrupting growth of the GaAs host material but continuing doping. Photoluminescence measurements on this new superlattice at 2 and 77 K reveal high-intensity emission at energies below the band gap of the GaAs host material. The luminescence energy does not depend on the excitation density over five orders of magnitude. This result indicates short minority-carrier lifetimes even at low-density excitation and a stable low-energy band gap of the superlattice. The spontaneous carrier lifetime determined from high-intensity excitation amounts to 3.3 ns, which is comparable to bulk-type GaAs. The material design parameters for the new superlattice are established taking into account quantized electron and hole states in the V-shaped potential wells.