Monte Carlo calculation of electron relaxation times in perfect and disordered quantum wire laser structures

Abstract

We calculate the electron relaxation times in GaAs quantum wires of 100×100 Å and 200×200 Å cross sections by a Monte Carlo simulation with the inclusion of electron-phonon and electron-electron interactions for the wire band structure computed by solving the one-band Schrödinger equation with and without structural disorder at the wire interface. The electron relaxation time is found to be greater than a hundred picoseconds for the 100×100 Å wire, while it is approximately 10 ps for the wire with the 200×200 Å cross section with the results converging to the case of bulk material for increased wire cross section. The influence of disorder on carrier relaxation in quantum wires is found to be negligible. The unusually slow carrier equilibration process is attributed to the combined effect of the sharply peaked one-dimensional density of states and the absence of randomizing intrasubband carrier-carrier scattering processes in quasi-one-dimensional systems. The dependence of electron relaxation times on the size of the quantum wire appears to be extremely sensitive.