P-Channel GaN transistor based on p-GaN/AlGaN/GaN on Si

In this letter, we demonstrate a recessed-gate p-channel MISFET using a p-GaN (70 nm)/Al _0.2Ga_0.8N (15 nm)/GaN heterostructure grown by metalorganic chemical vapor deposition (MOCVD) on a Si substrate. A major benefit of such epi-structure is that it contains both a 2-dimensional electron gas (2-DEG) and a 2-dimensional hole gas (2-DHG), hence making it suitable for the GaN-based complementary circuit implementation. In addition, the 2-DEG at the interface of the AlGaN/GaN heterostructure is depleted due to the p-GaN layer on top giving rise to normally- OFF operation for the n-channel transistors. A contact resistivity of 4.9 × 10^-6Ω · cm² is obtained for the ohmic contact to the hole channel for a p-GaN Mg concentration of 2 × 10²⁰ cm^-3. Long channel (L_g = 3 μm and Lsd = 9 μm) p-type transistors show an ON-OFF current ratio of ~10⁵ and ON resistance of ~2.3 kΩ · mm at V GS = -11 V.