Energy exchange between heterostructure layers by realhyphen;space electron transfer

摘要

Using Monte Carlo simulation we investigate electron transport in GaAshyphen;nhyphen;AlxGa1minus;xAs heterostructure with high electric field applied parallel to the layer interface. Within a threehyphen;dimensional electron gas model we study the energy exchange between adjacent layers caused by realhyphen;space electron transfer (RSET). We have calculated anxhyphen;dependent electron temperatureTe(x), withxbeing the distance from the interface, and distribution functionf(kx,x), wherekxis a wavehyphen;vector component perpendicular to the interface.Te(x) behavior clearly shows that the energy exchange between layers occurs: the electron temperature in the GaAs layer (high mobilitymdash;strong heating by field) is lower and that in thenhyphen;AlxGa1minus;xAs layer (low mobilitymdash;weak heating by field) is greater than the corresponding bulk values. A peculiar feature of the electron temperaturexdependence is its abrupt change at the interface. We have shown that the presence of temperature step is necessary for the energy exchange due to RSET and it should be present in parallel transport simulations of threehyphen;dimensional electron gas where modulation doping of layers and smooth interfaces with abrupt potential barriers are considered. Compared to bulk distributions, the results forf(kx,x) are visibly influenced both by RSET and energy exchange. All numerical results are interpreted using simple general considerations. Finally, it is discussed that increased electron temperature in thenhyphen;AlxGa1minus;xAs layer can lead to more effective thermionic emission back to the GaAs layer, and thus increases the speed of the RSET oscillator.