Electron transport in a short As/GaAs superlattice

Abstract

We report an experimental and theoretical study of electron transport in short (∼200 nm) Al 0.265 Ga 0.735 As/GaAs n-type superlattices. In order to make the results of this investigation relevant to quantum-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 associated with tunnelling negative differential resistance was observed in some of our devices. Standard theoretical expressions were used for the thermal and tunnelling components in each section of the device. At higher biases Fowler-Nordheim tunnelling was used to explain the rapid increase in current with voltage. The critical roles of well capture, confined level broadening and built-in voltages were identified. Satisfactory agreement between theory and experiment was obtained and this allowed an estimate of level broadening to be made.

Monte Carlo Modeling of Electron Transport and Capture Processes in AlGaAs/GaAs Multiple Quantum Well Infrared Photodetectors

“…The vertical electron mobilities calculated for QWIPs at T = 77 K are in the range µ (1.0-1.5) × 1000 cm 2 /V•s, which are not unreasonable. 32,33) Figures 1 and 2 demonstrate that the vertical saturation velocities for QWIPs with different parameters are approximately equal to 10 7 cm/s. The calculated vertical mobilities and velocities in QWIPs (for T = 77 K) are somewhat below the values obtained from experiments 22) at T = 15 K.…”

Temperature dependent carrier escape from quantum well states in GaAs/GaAlAs graded index laser structures

“…However additional balance considerations [13] are needed because preferential escape of one carrier type is similar to trapping of the other type and would build up an internal potential that could modify the biasing field due to the doping profile of the pin structure. This question is especially important for MQW structures and has been intensively studied for QWIPs [16].…”

Temperature and electric field dependences of the mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures containing quantum wells

“…Barrier structures with rectangular potential barriers have been studied extensively (see [1]). Recently, Ridley and coworkers [2][3][4][5][6] investigated vertical transport in GaAs/Ga 1− Al As barrier structures with linearly graded barriers grown between the n + -GaAs contacts and the central barrier containing N (=0, 2, 4, 7 and 10) quantum wells. Bishop et al [4] measured the electron mobility as a function of temperature in the range 77-300 K by applying low voltage (0.01 V) to the samples with N =4, 7 and 10.…”