Scaling and carrier transport behavior of buried-channel In_0.7Ga_0.3As MOSFETs with Al₂O₃ insulator

In this paper, we investigate the scaling and carrier transport behavior of sub-100 nm In_0.7Ga_0.3As buried-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with Al₂O₃ as gate dielectric. The device combines a 3-nm Al₂O₃ layer grown by atomic-layer-deposition (ALD) and a 13-nm In_0.52Al_0.48As insulator grown by molecular-beam-epitaxy (MBE). Our long channel device with L_g = 200 nm exhibits excellent subthreshold characteristics, such as subthreshold-swing (S) of 68 mV/decade at V_DS = 0.5 V, indicating a very good interface quality between Al₂O₃ and In_0.52Al_0.48As. In addition, a short-channel device with L_g = 60 nm maintains electrostatic integrity of the device, such as subthreshold-swing (S) = 90 mV/decade and drain-induced-barrier-lowering (DIBL) = 100 mV/V at V_DS = 0.5 V. We show well-behaved electrostatic scaling behavior that follows a modified FD-SOI MOSFET model. Our experimental and theoretical research suggest that further device optimization in the form of a self-aligned contact structure and aggressive EOT scaling would lead to high-performance III-V MOSFETs for multiple types of applications.