Temperature-dependent behavior of regular and trench Ni/β-Ga2O3 (001) Schottky barrier diodes (SBDs) was studied. Current–Voltage (I–V) characteristics, ideality factor, and barrier height of trench SBDs were compared with those of regular SBDs at temperatures ranging from 100 K to 650 K. The trench SBDs showed a superior performance to regular SBDs. At elevated temperatures (as high as 650 K), the trench SBDs maintained a high ON/OFF current ratio (105), which is four orders of magnitude higher than that in the regular diodes. The current–voltage characteristics of the trench SBDs were recovered when the sample was cooled to room temperature after high temperature measurements, whereas the I–V characteristics of the regular SBDs were degraded. The breakdown voltage (BV) was also measured on as-fabricated devices and after high temperature ramp up to 650 K. We observed a reduction in maximum achieved BV from 1084 V to 742 V on the trench SBDs and from 662 V to 488 V on regular SBDs, respectively, after temperature-dependent measurements.
In this Letter, the interface state density (Dit) and bulk trap density (nbulk) in post-deposition annealed Al2O3/β-Ga2O3 (001) metal–oxide–semiconductor capacitors (MOSCAPs) are extracted using the deep UV-assisted capacitance–voltage method and an improved physical analytical model. The effects of atomic layer deposition (ALD) temperature and post-deposition annealing (PDA) conditions are also studied. Increasing the deposition temperature and PDA at 500 °C in O2 seems to be an effective way to improve the forward breakdown voltage (BV) and suppress capacitance–voltage hysteresis in Al2O3/β-Ga2O3 (001) MOSCAPs. These results are useful for future high performance Ga2O3-based metal-oxide-semiconductor field effect transistors (MOSFETs) and Fin-FETs.
Dry etching behavior of unintentionally-doped α-Ga 2 O 3 was investigated in a BCl 3 /Cl 2 /Ar chemistry using inductively-coupled-plasma technique. We systematically studied the impact of various etch conditions such as BCl 3 /Cl 2 /Ar gas ratio, plasma and bias powers, and chamber pressure on etch rate, surface roughness and mask selectivity of α-Ga 2 O 3 with respect to Si 3 N 4 , SiO 2 and photoresist. In contrast to GaN etching, Cl 2 was found to be far less effective than BCl 3 in etching α-Ga 2 O 3 .
The interface and bulk properties of aluminum-silicon-oxide (AlSiO) dielectric grown by metal-organic chemical vapor deposition (MOCVD) on (001) β-Ga2O3 were investigated systematically using a deep UV-assisted capacitance–voltage methodology. The improved surface preparation with a combination of UV-ozone and wet chemical treatment reduced near-interface traps resulting in a negligible hysteresis. An average interface state density of 6.63 × 1011 cm−2 eV−1 and AlSiO bulk trap density of 4.65 × 1017 cm−3 eV−1 were quantified, which is half of that for Al2O3 deposited by atomic layer deposition (ALD). A net positive interface fixed charge of 1.56 × 1012 cm−2 was measured. In addition, a high dielectric breakdown field of ∼7.8 MV/cm and more effective suppression of gate leakage were achieved on these devices compared with ALD-Al2O3 on similar metal-oxide-semiconductor (MOS) structures.
In this work, we studied the impact of post-metallization annealing (PMA) on interfacial and bulk dielectric properties of AlSiO/β-Ga 2 O 3 metal-oxide-semiconductor capacitors (MOSCAPs). Annealing at 300 • C improved the reverse operational stability within the test operation range from −10 V to −42 V. The near-interface fast and slow traps were both suppressed by PMA at 300 • C and 350 • C, leading to a negligible flat-band voltage hysteresis. The low gate leakage region was extended from 3.7 MV cm −1 to 4 MV cm −1 and the breakdown strength was improved from 7.8 MV cm −1 to 8.2 MV cm −1 for AlSiO/β-Ga 2 O 3 MOSCAPs with PMA at 300 • C compared with not-annealed samples. The superior operational reliability demonstrated in this work is useful for future high-performance and reliable MOS-based Ga 2 O 3 transistors.
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