Photoreflectance spectroscopy of GaInSbBi and AlGaSbBi quaternary alloys

摘要

Molecular beam epitaxy is used to grow Ga1− y In y Sb1− x Bi x (y ≤ 5.5% and x ≤ 2.5%) and Al y Ga1− y Sb1− x Bi x alloys (y ≤ 6.6% and x ≤ 2.0%). The alloy composition and film thickness are determined by high resolution x-ray diffraction. The band gap of the alloys is determined by photomodulated reflectance (PR) spectroscopy. The band gap energy reduces with increasing In and Bi contents and decreasing Al content. The band gap energy reduction between 15 and 290 K is in the range of 60–75 meV, somewhat lower than the 82 meV for GaSb. The broadening of the band gap-related PR feature is between 16 and 28 meV.