Investigation of temperature dependent threshold voltage variation of Gd2O3/AlGaN/GaN metal-oxide-semiconductor heterostructure

Temperature dependent threshold voltage (V-th) variation of GaN/AlGaN/Gd(2)O(3)w/Ni-Au structure is investigated by capacitance-voltage measurement with temperature varying from 25 degrees C to 150 degrees C. The V-th of the Schottky device without oxide layer is slightly changed with respect to temperature. However, variation of V-th is observed for both as-deposited and annealed device owing to electron capture by the interface traps or bulk traps. The V-th shifts of 0.4V and 3.2V are obtained for as-deposited and annealed device respectively. For annealed device, electron capture process is not only restricted in the interface region but also extended into the crystalline Gd2O3 layer through Frenkel-Poole emission and hooping conduction, resulting in a larger V-th shift. The calculated trap density for as-deposited and annealed device is 3.28x10(11)similar to 1.12x10(11) eV(-1)cm(-2) and 1.74x10(12)similar to 7.33x10(11) eV(-1)cm(-2) respectively in measured temperature range. These results indicate that elevated temperature measurement is necessary to characterize GaN/AlGaN heterostructure based devices with oxide as gate dielectric. Copyright 2012 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4750481]