Growth behavior of GaN on AlN for fully coalesced channel of AlN-based HEMT

Abstract

We investigated the growth behavior of GaN grown on AlN along with V/III ratio and pressure variation, and found out the lateral growth regime for the fully coalesced channel layer of the AlN-based double-hetero structure high electron mobility transistor (HEMT). When the V/III ratio increases and pressure decreases, compressive stress in the GaN channel increases, and pit formation occurs to release the stress. The AlN-based HEMT structure was grown and the device was fabricated with an optimized channel layer. The two-dimensional electron gas mobility, sheet density, and sheet resistance were 1480 cm2 V−1 s−1, 1.32 × 1013 cm−2, and 319 Ω/sq., respectively, at room temperature. The device was characterized; direct current output result showed that the maximum current was ∼620 mA mm−1, on-resistance was 6.4 Ω mm, transconductance was ∼140 mS mm−1, and current on/off ratio was ∼104, respectively.