Pressure dependence of the E1 gap in GaSb: Resonant Raman technique

A new method to determine the pressure dependence of energy gaps with the help of the diamond anvil cell is reported. The method is based on resonance Raman scattering observed as the gap energies cross the photon energies of several laser line. The technique is illustrated by means of measurements of the pressure dependence of the E₁ gap of GaSb up to the phase transition (7.7 Gpa). A sublinear dependence of the E₁ gap on pressure and a linear dependence on lattice constant (dE₁/dlnV = 4.67 ± 0.1 eV) is obtained. These results are well explained by pseudopotential calculations.