Transport Properties of High Mobility 2DEGs in AlGaN/GaN Heterostructures
Abstract
We report on the transport properties of a two-dimensional electron gas (2DEG) confined at the lower interface of a GaN/Al_0.06Ga_0.94N/GaN heterostructure grown by molecular beam epitaxy on semi-insulating GaN templates prepared by hydride vapor phase epitaxy. Using an insulated gate Hall bar structure, the electron density is continuously tuned from 2x10^12cm-2 down to 1.5x10^11cm-2. At T=300mK, the 2DEG displays a maximum mobility of 80,000cm^2/Vs at a sheet density of 1.75x10^12cm-2. At low densities, the mobility exhibits a power law dependence on density- μ n_e^α, with α 0.83, over the range of 2x10^11cm-2 to 1x10^12cm-2. In this density regime, the mobility is no longer limited by alloy scattering and long-range Coulomb scattering dominates. The 2DEG remains metallic at a density of 1.5x10^11cm-2 at T=300mK. We discuss the dominant scattering mechanisms that presently limit low temperature mobility at electron densities below 1x10^12cm-2. In addition we discuss the ratio of quantum to mobility lifetimes in our structures and its implications for the relative importance of large and small angle scattering in the AlGaN/GaN system. High magnetic field studies of the integer and fractional quantum Hall effect are also presented.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARH10001M