Gamma and X Bandgap Hydrostatic Deformation Potentials for epitaxial In sub (0.52) Al sub (0.48) As on InP(001).

The pressure dependence of the direct and indirect bandgap of epitaxial In sub (0.52)Al sub (0.48) As on InP(001) substrate has been measured using photoluminescence up to 92 kbar hydrostatic pressure. The bandgap changes from GAMMA to X at an applied pressure of ~ 43 kbar. Hydrostatic deformation potentials for both the GAMMA and X bandgaps are deduced, after correcting for the elastic constant (bulk modulus) mismatch between the epilayer and the substrate. For the epilayer we obtain ( XI sub d + 1 over 3 XI sub u - a) as -(6.92 +- 0.3)eV and +(2. 81 +- 0.15)eV for the GAMMA and X bandgaps, respectively. From the pressure dependence of the normalized GAMMA-bandgap photoluminescence intensity a GAMMA-X lifetime ratio, ( tau sub GAMMA / tau sub X ), of 4.1 X 10 sup (-3) is deduced.