Experimental Evidence for Optical Population of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>X</mml:mi></mml:math>Minima in GaAs

Abstract

Electrons photoexcited in ${p}^{++}$-GaAs (with Cs surface monolayer) are found to "thermalize" in either the $\ensuremath{\Gamma}$ or $X$ conduction-band minima while diffusing to the surface. Two strong peaks separated by 0.3 eV of photoemitted electrons associated with these minima are observed in the energy distribution curves for $1.5 \mathrm{eV}&lt;~h\ensuremath{\nu}&lt;~3.2 \mathrm{eV}$.