WELL-WIDTH DEPENDENCE OF INTERFACE ROUGHNESS SCATTERING IN GAAS GA1-XALXAS QUANTUM-WELLS/

Well-width dependence of quantum and transport mobilities of electrons in GaAs/GaAlAs multiple quantum wells is studied for wells with width s ranging between 50 Angstrom and 145 Angstrom. Experimental results a re obtained from the amplitude analysis of the Shubnikov-de Haas (SdH) oscillations and from conventional Hall measurements at temperatures between T = 15 K and 4.2 K. A novel technique is employed to estimate, theoretically, the interface roughness parameters from electron quant um and transport lifetimes. The modelling is carried out for a range o f layer fluctuations, width (Delta) and lateral size (Lambda), as to o btain the best fit to the experimental results for individual samples. Our results indicate that the interface roughness scattering limits e qual both quantum and transport mobilities at low temperatures, and th at the nature of scattering by interface roughness (small or large ang le) depends not only on the size and the width of the fluctuations but also on the distribution of these fluctuations within the samples. Th erefore, unlike the predictions of the existing theoretical models, wh ich assume constant values of Delta and Lambda for all well widths, th e well-width dependence of interface roughness scattering cannot be ve rified experimentally. (C) 1997 Academic Press Limited.