Ultrawide bandgap Al x Ga1–x N channel heterostructure field transistors with drain currents exceeding 1.3 A mm−1

We report an Ultrawide Bandgap Al0.4Ga0.6N channel metal-oxide-semiconductor heterostructure field effect transistor with drain currents exceeding 1.33 A mm−1 (pulse) and 1.17 A mm−1 (DC), around a 2-fold increase over past reports. This increase was achieved by incorporating a hybrid barrier layer consisting of an AlN spacer, n-doped Al0.6Ga0.4N barrier and a thin reverse graded AlxGa1–xN (x from 0.60 to 0.30) cap layer. To enhance current spreading, a "perforated" channel layout comprising of narrow channel sections separated by current blocking islands was used. A composite ALD deposited ZrO2/Al2O3 film was used as gate dielectric. A breakdown field above 2 MV cm−1 was measured.