On the thermal oxidation of AlInN/AlN/GaN heterostructures

Abstract

In this work, we report on the thermal oxidation of AlInN/AlN/GaN heterostructures. A ‘nearly‐native’ Al2O3 oxide was formed during this procedure, which can be used as a gate oxide and thus enables the fabrication of MIS‐HFET. 2DEG density and, in particular, carrier mobility are strongly affected by the thermal treatment in O2 atmosphere. Hence, only a narrow processing window for successful thermal oxidation was identified, covering annealing temperatures between 700 °C and 800 °C and annealing durations of few minutes. Oxide thicknesses estimated to be in the range of 0.6 nm and 2.6 nm were fabricated, enabling a suppression of reverse leakage currents of MIS large‐area gate diodes by up to three orders of magnitude. The resulting oxide thickness scales well with the square root of oxidation time, indicating a diffusion of oxygen atoms into the barrier. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermal Oxidation of AlInN for III-Nitride Electronic and Optoelectronic Devices

“…The resulting oxidation rates are faster and the oxide is thicker than thought possible, mainly based on previous reports that suggest only surface oxides are possible with dry O 2 oxidation. 15 The ability to form oxide layers in III-nitrides creates the possibility for new device applications such gate oxides and optical confinement structures for waveguides.…”

“…Wet thermal oxidation of AlInN has yet to be reported in the literature. There have been prior demonstrations on the oxidation of AlGaN and AlInN, including the oxidation of AlGaN , and AlInN in dry (O 2 ) atmospheres resulting in thin layers < 10 nm that are primarily for passivation and charge control in high-electron-mobility transistors (HEMTs). On the basis of these studies the prevailing notion is that Al-based III-nitride layers are limited in overall thickness.…”

“…The oxidation of Al 0.82 In 0.18 N forms an oxide with high resistivity, a low refractive index, low extinction coefficients (loss), and smooth surface morphology, making it an excellent oxide to create electronic and optoelectronic devices. The resulting oxidation rates are faster and the oxide is thicker than thought possible, mainly based on previous reports that suggest only surface oxides are possible with dry O 2 oxidation . The ability to form oxide layers in III-nitrides creates the possibility for new device applications such as gate oxides and optical confinement structures for waveguides.…”