First monolithic integration of GaN-based enhancement mode n-channel and p-channel heterostructure field effect transistors

GaN-based devices have shown to be promising alternatives to Si-based devices in a wide range of applications. After covering several frequency bands in RF power amplification, GaN-based devices also penetrate into the power-switching market. Owing to the high carrier density and the high mobility in a 2-D electron gas (2DEG) and a large bandgap, GaN-based devices have shown great performance. These properties may also be exploited in digital logic applications, for which complementary logic offers the lowest power consumption. Hence, p-channel devices which employ a 2-D hole gas (2DHG) have attracted increasing research interest lately [1,2]. The recent progress of p-channel device characteristics [1] finally enables the monolithic integration of p- and n-channel transistors. Hence, complementary logic on basis of GaN (C-GaN) is within reach. As a first step towards C-GaN, the first report on the integration of enhancement mode (e-mode) n- and p-channel devices on a single wafer is presented. Challenges encountered are discussed and a first voltage transfer characteristic of an inverter structure is shown.