PERPENDICULAR ELECTRON-TRANSPORT IN GAAS ALGAAS MULTIPLE-QUANTUM WELLS STUDIED BY JUNCTION SPACE-CHARGE TECHNIQUES/

Transient capacitance and admittance spectroscopy techniques have been used to investigate the perpendicular electron transport properties o f GaAs/AlGaAs multi-quantum welts. Two transport processes have been s tudied at weak electric fields: thermionic transport over the barriers and tunnelling processes through the barriers. Purely exponential tim e dependences have been observed in both cases and the transport rates could therefore be directly measured and compared with theory. The co nduction band offset at the GaAs/AlGaAs interface was determined using both measurement techniques and compared with previously published da ta.