Quantum confinement effect on the effective mass in two-dimensional electron gas of AlGaN/GaN heterostructures

We report the results of direct measurements and a theoretical investigation of the in-plane effective mass in the two-dimensional electron gas of nominally undoped AlGaN/GaN heterostructures with a different degree of quantum confinement. It is shown that in most cases the conduction band nonparabolicity effect is overestimated and the electron wave-function penetration into the barrier layer should be taken into account. The contribution of the wave-function hybridization is determined to play the dominant role. The band edge effective mass value is deduced to be (0.2 +/- 0.01)m(0). (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3100206]