Alloy disorder limited mobility of InGaN two-dimensional electron gas

Abstract

The mobility of an InGaN based two-dimensional electron gas is determined for an indium content ranging from 0 to 20%. While the electron density remains constant at ∼2.5 × 1013 cm−2, the room-temperature mobility drastically decreases from 1340 to 173 cm2 V−1 s−1 as the In content increases. In fact, the mobility already drops below 600 cm2 V−1 s−1 for an In content as low as 3%. A theoretical model including random alloy fluctuations reproduces well the experimental data confirming that alloy disorder is the main scattering mechanism. With the aim of probing how sensitive the electron mobility is to the InGaN channel/barrier interface, a very thin GaN interlayer was inserted. A dramatic increase in the mobility is observed even for 2 nm of GaN, shedding light on the impact of unintentional GaN interlayers, which may form upon growth conditions or reactor-associated parasitic deposition.