Performance Enhancement of Normally-Off Plasma-Assisted Atomic Layer Deposited Al2O3/GaN Metal–Oxide–Semiconductor Field-Effect Transistor with Postdeposition Annealing

概要

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A normally-off GaN-based metal–oxide–semiconductor field effect transistor (MOSFET) was fabricated using the Al0.3Ga0.7N/GaN heterostructure with a two-dimensional electron gas (2DEG) density of ${\sim}1\times 10^{14}$ cm-2 grown on a silicon substrate. The AlGaN layer in the gate region was fully recessed and the whole surface of the device was covered with a high-quality plasma-assisted atomic-layer-deposited (PAALD) Al2O3 layer, which plays the role of not only a gate insulator in the recessed gate region, but also a surface passivation layer in the ungated region between the source and the drain. The fabricated Al2O3/GaN MOSFET exhibited excellent device properties, such as a threshold voltage of 1.1 V extrapolated in the linear region at a drain voltage of 0.1 V, maximum drain current of 353 mA/mm, field-effect mobility of 225 cm2$\cdot$V-1$\cdot$s-1, and on-resistance of 9.7 $\Omega$$\cdot$mm, which are among the best values ever reported for GaN MOSFETs fabricated on silicon substrates.
2010-12-25