A low temperature controlled annealing technique was utilized to improve the performance of vertical β-gallium oxide (β-Ga₂O₃) Schottky barrier diodes (SBDs) in this work. The nickel is diffused into Ga₂O₃, and NiO was formed at the interface between the anode and semiconductor generating p–n junction after low temperature annealing. Simultaneously, the trap state density of interface Ni/Ga₂O₃ as well as the carbon bonded with oxygen on the surface was reduced, which was proved by the capacitance and conductance measurements and x-ray photoelectron spectroscopic analysis, respectively. Combined the decreased saturation current density by three orders of magnitude from 1.21 × 10⁻⁶ to 9.27 × 10⁻⁸ and 5.12 × 10⁻⁹ A/cm² and larger breakdown voltage from 220 to 270 V owing to the optimized interface and the formation of NiO, a low temperature annealing technique makes certain effective improvement for vertical β-Ga₂O₃ SBDs via interface engineering.

A β-Ga₂O₃ Schottky barrier diode (SBD) with a p-type NiO_x guard ring was fabricated, and the reverse leakage and subthreshold leakage current reduction was found at high temperatures from temperature-dependent I–V characteristics. The functional mechanisms of NiO_x as edge termination on leakage reduction were studied. NiO_x can increase the barrier height and passivate the defects at the interface, resulting in the suppression of subthreshold leakage and elimination of current crowding effect confirmed by a thermal emission microscope. From the temperature-dependent x-ray photoelectron spectroscopy characteristics, more holes generated to deplete Ga₂O₃ at higher temperatures were found. It leads to reduce the reverse leakage current. The small-polaron transportation in NiO_x is proposed to argue the implausibility of the leakage conduction in NiO_x. This work will offer critical physical insight and a valuable route for developing low-leakage Ga₂O₃ SBDs.

This Letter reports two kinds of oxygen-containing plasma treated β-Ga2O3 Schottky barrier diodes (SBDs), including N2O plasma treatment and O2 plasma treatment, and the SBD without plasma is prepared for comparison. I–V characteristics, breakdown characteristics, and trap state characteristics of three devices have been studied. It is found that the turn-on voltage of SBDs with N2O plasma can reduce to 0.6 V, and the better current density of 750 A/cm2 and an on-resistance of 3.5 mΩ cm2 are obtained after the N2O plasma treatment. Moreover, the breakdown voltage of SBDs with N2O plasma is 50.2% higher than the conventional one, whose value reaches 323 V. In addition, the trap states' characteristics of the devices are studied, which show that the oxygen-containing plasma can reduce the deep level trap states density partly in the anode region, which can improve the surface quality effectively.

In this paper, a high-performance multi-channel heterostructure based on lattice-matched AlInN/GaN has been reported. The stacking of five heterostructures yields a high two-dimensional electron gas density of 3.67 × 10¹³ cm⁻² and a small sheet resistance (R_SH) of 74.5 Ω/sq. Compared with the AlGaN/GaN sample with the same number of heterojunctions, the AlInN/GaN sample reduces the R_SH by 51.2%. Since the AlInN barrier and GaN channel are lattice-matched, the strain defects caused by piezoelectric strain can be alleviated. The high-resolution x-ray diffraction results show that the total dislocation density in AlInN/GaN multi-channels is reduced by 18.9%. The calculation models of multiple-channel heterostructures are obtained to investigate the electron population and energy band diagram, and the calculated results are roughly consistent with the experimental results. With a gate–drain spacing of 11.5 μm, the on-resistance (R_ON) of the AlInN/GaN multi-channel HEMT was only 2.26 Ω mm, indicating that the lattice-matched multi-channel AlInN/GaN heterostructure can substantially enhance the current drive efficiency and improve the output performance of the devices.