A metal/n-Ga2O3/p-diamond heterojunction diode with superior high-temperature performance was demonstrated in this work. The p-type diamond was lightly boron doped, and the Ga2O3 film was grown via atomic layer deposition without intentional doping. The forward current density increased with temperature, while the reverse current decreased at elevated temperatures. This behavior was attributed to the distinct carrier ionization dynamics across varying temperature ranges. Under high reverse voltage stress, the reverse current remained relatively stable, with no breakdown occurring up to 498 K. An avalanche breakdown voltage of 186 V at 498 K indicates the diode's robust high-voltage endurance capability. These findings underscore the potential of the metal/n-Ga2O3/p-diamond heterojunction diode for high-temperature and high-voltage applications.

As an ultrawide-bandgap semiconductor, Ga2O3 has promising applications in electronics and optoelectronics. ɛ-Ga2O3 has attracted much attention as it performs the polarization effect, whereas single-phase and preferentially oriented ɛ-Ga2O3 films have not been prepared by the atomic layer deposition (ALD) method at low temperatures. In this paper, Ga2O3 films are prepared on sapphire substrates through the ALD method at different substrate temperatures and using different O sources. The x-ray reflectivity measured thicknesses and x-ray photoelectron spectroscopy spectra both demonstrate that the Ga source of triethylgallium cannot reacts continuously with the O source of H2O layer-by-layer. The growth rates of Ga2O3 films using O3 or PE-O2 as the O source range from 0.342 to 0.448 Å/cycle. X-ray diffraction (XRD) results indicate that the as-grown Ga2O3 films at 250 °C are amorphous, no matter using O3 or PE-O2 as the O source. They both crystallize into the single-phase and (−201) preferentially oriented β-Ga2O3 films after a high-temperature annealing of 900 °C. When the growth temperature rises to 350 °C, single-phase and (0002) preferentially oriented ɛ-Ga2O3 films occur if using PE-O2 as the O source. The full width at half maximum for the (0004) plane of ɛ-Ga2O3 from the XRD rocking curve is 0.937° while the atomic force microscopy measured surface roughness RMS is 1.24 nm. The crystal structure of the as-grown ɛ-Ga2O3 films can be maintained at an annealing temperature of 700 °C and they transform into polycrystalline β-Ga2O3 films at 900 °C. The results are beneficial for the applications of Ga2O3-based microelectronic devices.

A plasma refractive index sensor based on metal–insulator–metal waveguide-coupled analogy T-shaped with double-ring resonators was designed. The transmission characteristics of the waveguide were investigated using the finite-difference time-domain method with perfectly matched layer absorbing boundary conditions. By optimizing the structure parameters, the sensor obtained the maximum sensitivity (S) of 1110 nm/RIU and the maximum figure of merit of 1904. The results demonstrate that this new structure can generate dual Fano resonances and exhibit typical refractive index sensing functionality, which provides valuable insights into the design and optimization of plasma refractive index sensors. Additionally, by measuring the concentration of plasma solution and glucose solution, it has been proven that the structure has the prospect of practical application.

A mild two-step method of black phosphorus (BP) flake thinning was demonstrated in this article. Slight ultraviolet–ozone (UVO) radiation followed by an argon plasma treatment was employed to oxidize mechanically exfoliated BP flakes and remove the surface remains of previous ozone treatment. The annealing process introduced aims to reduce impurities and defects. Low damage and efficient electronic devices were fabricated in terms of controlling the thickness of BP flakes through this method. These results lead to an important step toward the fabrication of high-performance devices based on two-dimensioned materials.

A highly sensitive and stable temperature sensor based on a diamond-Ga₂O₃ Schottky-pn diode is demonstrated in this work. The forward current exhibits a pronounced temperature dependence, with the turn-on voltage shifting from 2.08 V to 1.06 V as the temperature increases from 298 K to 523 K. A superior linearity is observed between the sub-threshold forward voltage drop at a constant current and temperature. A high voltage sensitivity is extracted to be around 4.38 mV/K at 100 nA. The sensitivity decreases with current increasing, but remains higher than 3 mV/K at 100 μA, highlighting the excellent performance of the diamond-Ga₂O₃ Schottky-pn diode as a temperature sensor. The device demonstrates a good repeatability at high current regions, indicating its potential for high-temperature sensing applications.

The larger open-circuit voltage (V_oc) and fill factor (FF) of the wide bandgap perovskite solar cells are limited by the inferior non-radiative recombination and energy level mismatch at the buried interface. Herein, we demonstrate a cooperative interface optimization strategy to suppress buried film defects and improve the efficiency. The self-assembled monolayer (SAM) layer of (4-(7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (4PADCB) was adopted as the hole transport layer (HTL) to replace the [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl] phosphonic acid (Me-4PACz), resulting in the effective carrier transport and the suppressed non-radiative interface recombination. Moreover, the KI buffer layer is introduced to form better energy alignment and passivate interface defects. As a result, the devices with 4PADCB/KI exhibited a better power conversion efficiency (PCE) of 22.55% with a higher FF of 83.6% and a larger V_oc of 1.265 V. Based on the fabricated wide bandgap perovskite solar cells, the four-terminal perovskite/crystalline silicon tandem solar cells and large-area modules achieve a tandem efficiency of 30.22% and a module efficiency of 18.21% with an effective area of 60.72 cm², respectively.