ELECTRON-TRANSPORT IN A SHORT AL0.265GA0.735AS GAAS SUPERLATTICE/

We report an experimental and theoretical study of electron transport in short (similar to 200 nm) Al0.265Ga0.735As/GaAs n-type superlattice s. In order to make the results of this investigation relevant to quan tum-well infrared photodetectors, our devices had wide barriers at the contacts to reduce dark current. Transport involved both thermal and tunnelling components, in general, throughout the temperature range 77 -300 K. At a critical high current superlattice domain formation assoc iated with tunnelling negative differential resistance was observed in some of our devices. Standard theoretical expressions were used for t he thermal and tunnelling components in each section of the device. At higher biases Fowler-Nordheim tunnelling was used to explain the rapi d increase in current with voltage. The critical roles of well capture , confined level broadening and built-in voltages were identified. Sat isfactory agreement between theory and experiment was obtained and thi s allowed an estimate of level broadening to be made.