Width dependence of quantum lifetimes in GaAAs heterostructures

We have studied the channel width dependence of quantum lifetimes (Formula presented) (or equivalently the quantum mobilities (Formula presented)=e(Formula presented)/m*) for samples with the widths w of 2-50 μm fabricated from three GaAs/(Formula presented)(Formula presented)As wafers. (Formula presented)estimated from the amplitude of Shubnikov-de Haas oscillations is found not to be affected by the asymmetry of Shubnikov-de Haas peaks and the boundary scattering observed in narrow samples. However, the two- to one-dimensional crossover occurring at w<(Formula presented) (thermal diffusion length) leads to the reduction of (Formula presented). In addition, we have also carried out similar measurements with the sample illuminated with a red light-emitting diode. The results obtained from the illuminated samples confirm those from the unilluminated samples.