Quantum transport in weakly coupled superlattices at low temperature

Abstract

We report on the study of the electrical current flowing in weakly coupled superlattice (SL) structures under an applied electric field at very low temperature, i.e. in the tunneling regime. This low temperature transport is characterized by an extremely low tunneling probability between adjacent wells. Experimentally, I(V) curves at low temperature display a striking feature, i.e a plateau or null differential conductance. A theoretical model based on the evaluation of scattering rates is developed in order to understand this behaviour, exploring the different scattering mechanisms in AlGaAs alloys. The dominant interaction in usual experimental conditions such as ours is found to be the electron-ionized donors scattering. The existence of the plateau in the I(V) characteristics is physically explained by a competition between the electric field localization of the Wannier-Stark electron states in the weakly coupled quantum wells and the electric field assisted tunneling between adjacent wells. The influence of the doping concentration and profile as well as the presence of impurities inside the barrier are discussed

Quantum well infrared photodetectors hardiness to the nonideality of the energy band profile

“…In our range of energy and for the operating temperature of our device, phonon processes are inefficient source of transport, see tab I. Clearly, for this structure, the interaction between electron and ionized impurities is the one which drives the transport 6 . The evolution of the intrawell scattering rate for the lowest subband has been simulated, this scattering rate is almost constant to 1.1×10 13 Hz with the gradient extension.…”

“…The following scattering processes are taken into account in our simulation: interaction between electron and LO phonons (LO), acoustical phonons (AC), alloy disorder (AL), interface roughness (IR), ionized impurities (II). Details of the scattering rates calculation are given in ref 6. The interaction between carriers has been neglected since this interaction is not dominant in this device 6 .…”

“…Details of the scattering rates calculation are given in ref 6. The interaction between carriers has been neglected since this interaction is not dominant in this device 6 . Simulations are performed in a double quantum well structure.…”

Quantum scattering engineering of quantum well infrared photodetectors in the tunneling regime

“…7 A change in the QWIP doping profile may thus allow a decrease in the dark current. 7 A change in the QWIP doping profile may thus allow a decrease in the dark current.…”

Determinação da corrente de escuro em fotodetectores de radiação infravermelha baseados em poços quânticos (QWIPs)

“…Os modelos mais comuns calculam a corrente devido ao tunelamento entre os poços, usando o conceito de minibanda [14] ou de estados localizados (Wannier-Stark) [15,12]. Devido à maior simplicidade do modelo de minibandas, este modelo foi utilizado neste trabalho de mestrado para auxiliar na interpretação dos dados experimentais.…”