Interface Engineering and Substitutional Doping in In₂Ge₂Te₆ for High-Performance 2D p-Type FETs and CMOS Devices

The metal-semiconductor contact interface is crucial for the performance of devices made from two-dimensional (2D) semiconductors, as it significantly influences the efficiency of charge carrier injection into the semiconductor channel. However, creating high-performance contacts for emerging 2D semiconductors, especially p-type semiconductors, presents several challenges. The performance of p-type devices is often limited by Fermi-level pinning and defect-mediated scattering at the interfaces, which create parasitic barriers that increase contact resistance. In this study, we focused on the low effective mass p-type semiconductor In₂Ge₂Te₆ to systematically explore the combined effects of interface contact and doping engineering on optimizing device performance. Introducing optimized electrode and region-selective oxygen doping reduced the Schottky barrier height from 63 to 36 meV and decreased the contact resistance from 1.3 to 0.6 kΩ µm, through matching work function and creating an impurity band that optimizes band alignment. Furthermore, we constructed an In₂Ge₂Te₆/MoS₂ complementary metal oxide semiconductor (CMOS) device, achieving an impressive voltage gain of 140 at V_DD = 5 V and a low peak static power consumption of 2.9 nW at V_DD = 1 V. This research presents a straightforward strategy for reducing contact barriers and enhancing performance in 2D p-type field-effect transistors (FETs) and CMOS devices.