Energy relaxation studies in In_(0.52)Al_(0.48)As/In_(0.53)Ga_(0.47)As/In_(0.52)Al_(0.48)As two-dimensional electron gases and quantum wires

摘要

We present Joule heating measurements carried out over a wide temperature range on two-dimensional electron gases (2DEGs) and quantum wires of varying widths fabricated in an In_(0.52)Al_(0.48)As/In_(0.53)Ga_(0.47)As/In_(0.52)Al_(0.48)As heterostructure system that has a 25 nm wide In_(0.53)Ga_(0.47)As quantum well region. The power dissipated per electron is extracted and the electron―phonon coupling processes in these systems are studied. The temperature decay of the power loss at the 2DEG points towards unscreened piezoelectric coupling to the acoustic modes over temperatures of 1―30 K, with boundary scattering in the ohmic contacts gaining importance at very low temperatures. In the wires, we observe different behaviour and the effect of wire width and carrier density on the observed energy-loss rates. Possible phonon confinement and exponential suppression in these structures are also looked at.