Acoustic and optic phonon energy relaxation in non-degenerate [formula omitted] multiple quantum wells

Abstract

Energy relaxation in two dimensional systems has recently been dominated by discussions concerning hot phonons associated with energy relaxation by optical phonons. We present results on energy relaxation in non-degenerate quantum wells in the acoustic and optic phonon regions. In the acoustic phonon region, below about 30K, we experimentally determine the power loss per carrier as a function of electron temperature, using the mobility field, mobility-temperature thermometric technique. We find that although the form of the function is the same as the current model, that is it is proportional to ( T e − T L ), the magnitude is not. In the light of this the current model is discussed and possible reasons for the anomaly suggested. In the region above 30K we find that our power loss per carrier data agrees favourably with data obtained using the hot electron photo-luminescence technique. These experimental results are fitted with a standard expression for energy loss via polar optical phonon scattering. This fitting yields 35.5 meV for the polar optical phonon energy and 245 fs for the phonon emission time.