We study experimentally and theoretically the influence of interface roughness on the mobility of twohyphen;dimensional electrons in modulationhyphen;doped AlAs/GaAs quantum wells. It is shown that interface roughness scattering is the dominant scattering mechanism in thin quantum wells with a well thicknessLw60 Aring;, where electron mobilities are proportional toL6w, reaching 2times;103cm2/Vthinsp;s atLwsim;55 Aring;. From detailed comparison between theory and experiment, it is determined that the lsquo;lsquo;GaAshyphen;onhyphen;AlAsrsquo;rsquo; interface grown by molecular beam epitaxy has a roughness with the height of 3ndash;5 Aring; and a lateral size of 50ndash;70 Aring;.
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