First-principles Predictions of Electronic Properties of GaAs1-x-yPyBix and GaAs1-x-yPyBix-based Heterojunctions

摘要

Significant efficiency droop is a major concern for light-emitting diodes andlaser diodes operating at high current density. Recent study has suggested thatheavily Bi-alloyed GaAs can decrease the non-radiative Auger recombination andtherefore alleviate the efficiency droop. Using density functional theory, westudied a newly fabricated quaternary alloy, GaAs1-x-yPyBix, which can hostsignificant amounts of Bi, through calculations of its band gap, spin-orbitsplitting, and band offsets with GaAs. We found that the band gap changes ofGaAs1-x-yPyBix relative to GaAs are determined mainly by the local structuralchanges around P and Bi atoms rather than their electronic structuredifferences. To obtain alloy with lower Auger recombination than GaAs bulk, weidentified the necessary constraints on the compositions of P and Bi. Finally,we demonstrated that GaAs/GaAs1-x-yPyBix heterojunctions with potentially lowAuger recombination can exhibit small lattice mismatch and large enough bandoffsets for strong carrier confinement. This work shows that the electronicproperties of GaAs1-x-yPyBix are potentially suitable for high-energy infraredlight-emitting diodes and laser diodes with improved efficiency.