Energy and momentum relaxation of electrons in GaAs/GaAlAs HEMT structures
Experimental results on high-field parallel transport in selectively doped GaAs/GaAlAs HEMT structures are reported. The results indicate that in lightly doped material (n=3.92*1011 cm-2), the effective rate of electron energy relaxation (EER) by LO phonons, is ( tau e) approximately 213 fs. This is about a factor of two faster than that in more heavily doped material (n=8.85*1011 cm-2). The high-field drift velocity saturates at nu ds=1.2*107 cm s-1 in the former and at nu ds=8*106 cm s-1 in the latter. The experimental results are compared with a model of high-field transport involving non-drifting hot phonon effects.