Electron scattering mechanisms at polar GaN/AlGaN interfaces

Leonardo Hsu; Wladek Walukiewicz

doi:10.1117/12.470415

11 June 2002 Electron scattering mechanisms at polar GaN/AlGaN interfaces

Leonardo Hsu, Wladek Walukiewicz

Proceedings Volume 4643, Ultrafast Phenomena in Semiconductors VI; (2002) https://doi.org/10.1117/12.470415
Event: Symposium on Integrated Optoelectronic Devices, 2002, San Jose, California, United States

Abstract

We present recent results of calculations of charge transfer and electron mobilities in nominally undoped AlGaN/GaN heterostructures. It has previously been proposed that the two-dimensional electron gas (2-DEG) originates from donor- like defects on the surface of the AlGaN barrier. We have made detailed calculations of a model in which these defects are created under thermodynamic equilibrium at the growth temperature and show that the spontaneous and strain-induced piezoelectric fields in the AlGaN barrier enhance the formation of these defects. In calculating the low temperature electron mobility in these structures, we consider all the major scattering mechanisms including acoustic phonons, Coulomb scattering from charged centers, and alloy disorder scattering. The relative importance of the different scattering mechanisms depends strongly on the 2-DEG density. At densities smaller than about 2x10¹²cm^-2, the mobility is limited by Coulomb scattering. At higher densities, alloy disorder scattering becomes the dominant electron scattering process. Finally, we have calculated the ratio of the transport to quantum lifetimes ((tau) _t/(tau) _q for various AlGaN/GaN heterostructures and find that the value of the ratio cannot be used to infer the nature of the dominant scattering mechanism, as is traditionally assumed.

Citation Download Citation

Leonardo Hsu and Wladek Walukiewicz "Electron scattering mechanisms at polar GaN/AlGaN interfaces", Proc. SPIE 4643, Ultrafast Phenomena in Semiconductors VI, (11 June 2002); https://doi.org/10.1117/12.470415

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