Pressure dependence of the electronic structure of a [311] piezoelectric Ga0.85In0.15As/AlAs superlattice

J. S. REPARAZ, L. R. MUNIZ, A. R. GONI, M. I. ALONSO, G. ROZAS, A. FAINSTEIN, S. SARAVANAN, AND P. O. VACCARO

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2010 vol. 82 p. 125306 - 125306

1098-0121

We have studied the electronic subband structure of a piezoelectric [311] Ga(0.85)In(0.15)As/AlAs superlattice by means of high-hydrostatic pressure and excitation-power-dependent photoluminescence at 78 K. In particular, we unraveled the origin of two optical transitions at around 1.96 and 2 eV at ambient pressure, which were recently found to give rise to an unexpectedly strong resonant enhancement of the acoustic-phonon Raman scattering for such samples with permanent built-in piezoelectric fields [G. Rozas et al., Phys. Rev. B 77, 165314 (2008)]. Here we demonstrate that these transitions are doubly indirect, in real and reciprocal space, corresponding to radiative recombination processes between electrons at the X valleys of the AlAs barriers and heavy holes at the Gamma point of the Brillouin zone but confined to the GaInAs quantum wells. In addition, the partial screening of the piezoelectric field induced by carrier photoexcitation under illumination becomes largely suppressed for pressures above 1.1 GPa due to conduction-band Gamma-X crossover effects.