Investigation of angstrom-thick aluminium oxide passivation layers to improve the gate lag performance of GaN HEMTs

Abstract

In this paper, we report an angstrom-thick atomic layer deposited (ALD) aluminum oxide (Al 2 O 3) dielectric passivation layer for an AlGaN/GaN high electron mobility transistor (HEMT). Our results show a 55% improvement in the gate lag performance of the design and a decrease by half in interface state density upon coating with two cycles of ALD Al 2 O 3. DC characteristics such as current density, threshold voltage, and leakage currents were maintained. ALD Al 2 O 3 passivation layers with thicknesses up to 10 nm were investigated. XPS analyses reveal that the first ALD cycles are sufficient to passivate GaN surface traps. This study demonstrates that efficient passivation can be achieved in atomic-scale with dimensions much thinner than commonly used bulk layers.

X-ray photoelectron spectroscopy study on effects of ultra-high-pressure annealing on surface of Mg-ion-implanted GaN

“…Here, the photoelectron take-off angle θ was set at 45 o . A Ga LMM Auger spectrum was decomposed into three components according to the literature 29,30) , whereas a Ga 3d spectrum was fitted by the combined Voigt function considering the spin-orbit doublet. The intensity was normalized to the area of the Ga 3d spectrum.…”

“…Here, the component A shown in Fig. 4 (b) for the as-implanted GaN is excluded in the calculation of the N 1s area because it should be assigned to the N-O bonding of the surface oxide 29,30) , although the reason why this component was remarkable at the Mg-I/I step is unclear. If nitrogen deficiency occurred, these ratios should become lower than those of the as-grown GaN.…”