The lifetime of optical phonons in a single heterostructure

作者：Dyson A^*; Ridley B K

来源：Journal of Applied Physics, 2011, 109(5): 054509.

DOI：10.1063/1.3553439

The lifetime of long-wavelength optical phonons in bulk semiconductors is known to be a function of electron density, decreasing with increasing density. An explanation of this has been given in terms of the effect of plasmon coupling on the anharmonic decay route. This explanation is limited to small wave vectors and is not applicable to the case of phonons in general because their interaction with electrons involves larger wave vectors for which the plasma coupling is Landau damped. Nevertheless, a similar decrease of lifetime with density is observed for hot phonons in the channel of a GaN Heterostructure Field Effect Transistor (HFET). We show that this dependence on electron density can be associated with the interaction with the barrier interface mode and the temperature dependence of the phonon lifetimes. It is pointed out that a complete account of the shortening of phonon lifetime in a working HFET requires an analysis of the specific thermal and electron transport properties of the system. Important differences arise between HFETs grown on sapphire and on SiC.

• 出版日期2011-3-1