Plasmons, photoluminescence, and band-gap narrowing in very heavily doped <i>n</i>-GaAs

Abstract

The optical properties of extremely heavily doped n-GaAs are examined. Metastable electron concentrations up to 3.2×1019 cm−3 were produced by pulsed-laser annealing of Si-implanted GaAs. These very heavily doped layers give plasmon Raman shifts up to 1700 cm−1 and photoluminescence bandwidths of greater than 410 meV. The low-energy edge of the photoluminescence indicates a band-edge narrowing proportional to ∼n1/3 and equal to ∼200 meV at the highest electron concentration.