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 0.2Ga0.8N (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 $\textsf {4.9}\times \textsf {10}^{-\textsf {6}}\Omega \cdot \textsf {cm}^{\textsf {2}}$ is obtained for the ohmic contact to the hole channel for a p-GaN Mg concentration of $\textsf {2}\times \textsf {10}^{\textsf {20}}\, \textsf {cm}^{-\textsf {3}}$ . Long channel ( ${L} _{\textsf {g}}=\textsf {3}\,\,{\boldsymbol \mu } \text{m}$ and ${L} _{\textsf {sd}}=\textsf {9}\,\,{\boldsymbol \mu } \text{m}$ ) p-type transistors show an ON–OFF current ratio of ~105 and ON resistance of $\sim 2.3~\text{k}{\Omega } \cdot \textsf {mm}$ at ${V} _{\textsf {GS}}=-\textsf {11}$ V.