THE LIGHT-HOLE MASS IN A STRAINED INGAAS/GAAS SINGLE-QUANTUM-WELL AND ITS PRESSURE-DEPENDENCE

The pressure dependence of the light-hole mass in a compressively strained In0.20Ga0.80As/GaAs single quantum well has been deduced from the temperature dependence of Shubnikov-De Haas oscillations over a pressure range from 0 to 15 kbar. The sample was grown by MBE on a GaAs substrate. Low-temperature hole densities in the well were (3.64 +/- 0.03) x 10(11) cm(-2) independent of pressure. The mass of (0.15 +/- 0.005)m(0) measured at atmospheric pressure agrees well with cyclotron resonance measurements reported elsewhere. The effective mass did not increase with pressure as expected but appeared to decrease between 0 and 8 kbar. It then remains constant with increasing pressure up to 15 kbar. Details of the experimental results are described and compared with theoretical calculations using a second-order 8-band k . p model. This predicts a mass which increases with pressure at a rate of about 0.5% kbar(-1) in disagreement with our experimental results, The importance of the warping of the valence band and the limitations of the model are described.