Growth and Properties of In_xGa_(1-x)As_ySb_(1-y) on GaSb

摘要

Lattice matched In_xGa_(1-x)As_ySb_(1-y) (y/x ≈ 0.9) quaternary alloy layers with 0 < x < 0.20 were grown by liquid phase epitaxy on (100) oriented GaSb. Based on optical transmission and electron microprobe measurements the dependence of the band gap energy on the alloy composition was established. The lowest band gap observed was ～0.55 eV. The dependence of the band gap on the composition exhibits smaller bowing than given by recent theoretical calculations based on the correlated function expansion technique. Near and below the fundamental absorption edge an exponential absorption tail corresponding to the Urbach rule was observed which is ascribed to the effects of the random potential due to the alloy disorder.