Determination of alloy scattering potential in Ga1−<i>x</i>Al<i>x</i>As alloys

Abstract

Room-temperature Hall mobility as a function of pressure (0–8 kbar) has been measured for high-purity liquid-phase-epitaxy-grown Ga1−xAlxAs layers. GaAs-like band structure of low-composition alloys has also been converted to Si-like band structure at high pressures and the Hall mobility measured as a function of temperature (77≲T≲300 °K) with crystals locked under constant pressures. The data have been analyzed to identify and distinguish the presence of space charge and alloy scatterings both characterized by mobilities limited by T−1/2. The space charge scattering has been found to be absent in all the crystals studied except x=0.047. The alloy scattering potential for electrons in the Γ minimum has been shown to depend on the alloy composition with a maximum value of 1.56 eV at x=0.19. For electrons in the X minima, this potential has been found to be independent of composition with a value of only 0.4 eV.