Electron Transport in GaAs Quantum Wells: Effect of Interface Roughness Scatterin

Authors: RITA GUPTA

Abstract: The importance of interface roughness (IFR) scattering of electrons and LO-phonons for electron transport in semiconductor quantum wells is discussed. Modulation doping of quantum wells minimizes the effect of impurity scattering on the low-field electron mobility so that IFR scattering of electrons in the well becomes the major limiting factor. A model calculation of IFR scattering of electrons in quantum wells is presented and it is shown that (both)\Lambda and \Delta, the parameters defining IFR, can be estimated by comparing the theoretical and experimental electron mobilities. The application of high electric field leads to a distribution of hot electrons which relax their energy and momentum through the emission of LO phonons. The dynamics of this non-equilibrium distribution of LO phonons greatly influences the electron transport at high fields. For example, a rapid momentum relaxation of hot LO phonons can lead to the saturation of electron drift velocity at high electric fields. Various mechanisms for momentum relaxation of LO phonons are presented and it is shown that IFR scattering is a major contributor to the non-drift of hot phonons. Implications for high-field electron transport in GaAs/AlGaAs quantum wells are discussed.

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