Improved Electrical Characteristics of Gallium Oxide/P-Epi Silicon Carbide Static Induction Transistors with UV/Ozone Treatment Fabricated by RF Sputter

In this study, static induction transistors (SITs) with beta gallium oxide (β-Ga₂O₃) channels are grown on a p-epi silicon carbide (SiC) layer via radio frequency sputtering. The Ga₂O₃ films are subjected to UV/ozone treatment, which results in reduced oxygen vacancies in the X-ray photoelectron spectroscopy data, lower surface roughness (3.51 nm) and resistivity (319 Ω·cm), and higher mobility (4.01 cm²V⁻¹s⁻¹). The gate leakage current is as low as 1.0 × 10⁻¹¹ A at V_GS = 10 V by the depletion layer formed between n-Ga₂O₃ and p-epi SiC at the gate region with a PN heterojunction. The UV/O₃-treated SITs exhibit higher (approximately 1.64 × 10² times) drain current (V_DS = 12 V) and on/off ratio (4.32 × 10⁵) than non-treated control devices.

Effect of Gas Annealing on the Electrical Properties of Ni/AlN/SiC

It is shown in this work that annealing of Schottky barrier diodes (SBDs) in the form of Ni/AlN/SiC heterojunction devices in an atmosphere of nitrogen and oxygen leads to a significant improvement in the electrical properties of the structures. Compared to the non-annealed device, the on/off ratio of the annealed SBD devices increased by approximately 100 times. The ideality factor, derived from the current-voltage (IV) characterization, decreased by a factor of ~5.1 after annealing, whereas the barrier height increased from ~0.52 to 0.71 eV. The bonding structure of the AlN layer was characterized by X-ray photoelectron spectroscopy. Examination of the N 1 s and O 1 s peaks provided direct indication of the most prevalent chemical bonding states of the elements.

Comparison of Temperature Sensing Performance of 4H-SiC Schottky Barrier Diodes, Junction Barrier Schottky Diodes, and PiN Diodes

We present a comparison between the thermal sensing behaviors of 4H-SiC Schottky barrier diodes, junction barrier Schottky diodes, and PiN diodes in a temperature range from 293 K to 573 K. The thermal sensitivity of the devices was calculated from the slope of the forward voltage versus temperature plot. At a forward current of 10 μA, the PiN diode presented the highest sensitivity peak (4.11 mV K^-1), compared to the peaks of the junction barrier Schottky diode and the Schottky barrier diode (2.1 mV K^-1 and 1.9 mV K^-1, respectively). The minimum temperature errors of the PiN and junction barrier Schottky diodes were 0.365 K and 0.565 K, respectively, for a forward current of 80 μA±10 μA. The corresponding value for the Schottky barrier diode was 0.985 K for a forward current of 150 μA±10 μA. In contrast to Schottky diodes, the PiN diode presents a lower increase in saturation current with temperature. Therefore, the nonlinear contribution of the saturation current with respect to the forward current is negligible; this contributes to the higher sensitivity of the PiN diode, allowing for the design and fabrication of highly linear sensors that can operate in a wider temperature range than the other two diode types.

Influence of Annealing Atmosphere on the Characteristics of Ga2O3/4H-SiC n-n Heterojunction Diodes

Ga₂O₃/4H-SiC n-n isotype heterojunction diodes were fabricated by depositing Ga₂O₃ thin films by RF magnetron sputtering. The influence of annealing atmosphere on the film quality and electrical properties of Ga₂O₃ layers was investigated. X-ray diffraction (XRD) analysis showed a significant increase in the peak intensities of different faces of β-Ga₂O₃ {(-201), (-401) and (002)}. X-ray photoelectron spectroscopy (XPS) measurement showed that the atomic ratio of oxygen increases under high-temperature annealing. Moreover, an N₂-annealed diode exhibited a greater rectifying ratio and a lower thermal activation energy owing to the decrease in oxygen-related traps and vacancies on the Ga₂O₃ film and Ga₂O₃-metal interface.