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

We investigated the growth behavior of GaN grown on AlN along with Ⅴ/Ⅲ ratio and pressure variation, and found out lateral growth regime for 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/Vs, 1.32 × 1013 cm-2, and 319 Ω/, respectively, at room temperature. The device was characterized; direct current output result showed that the maximum current was ~620 mA/mm, on-resistance was 6.4 Ωmm, transconductance was ~140 mS/mm, and current on/off ratio was ~104, respectively.