Two types of a trench with conventional vertical and new reverse-V-shaped cross-sections were fabricated on single crystal diamond (SCD) substrate using a micro-jet water-assisted laser. In addition, a microwave plasma chemical vapor deposition device was used to produce multiple micrometer-sized channels using the epitaxial lateral overgrowth technique. Raman and SEM methods were applied to analyze both types of growth layer characterization. The hollowness of the microchannels was measured using an optical microscope. According to the findings, the epitaxial lateral overgrowth layer of the novel reverse-V-shaped trench produced improved SCD surface morphology and crystal quality.

In this work, we fabricated a vertical diamond Schottky barrier diode (SBD) with a high breakdown electric field of 4.8 MV/cm and a forward current density of 2361 A/cm2. Compared with a regular diamond SBD, the breakdown electric field of SBD with a HfO2 field plate (FP) increased from 183 to 302 V, the current swing (ION/IOFF) was on the order of 1011. As the thickness of the HfO2 FP increased from 200 to 400 nm, the breakdown voltage of the SBD increased from 280 to 314 V, and the corresponding breakdown electric field increased from 4.5 to 5 MV/cm. We also measured the current–voltage characteristics at different temperatures to investigate the cause of the high on-resistance. As the measured temperature increased from 25 to 150 °C, the on-resistance of the device decreased from 4.7 to 1.7 mΩ·cm2. By studying the interface between HfO2 and the diamond, we found that HfO2 can reduce the interface state density of the Schottky contact. The interface state density of Zr/HfO2/diamond was lower than 1.5 × 1013 eV−1·cm−2. This work provides a simple strategy for realizing high-performance diamond SBDs.

A lower dislocation density substrate is essential for realizing high performance in single-crystal diamond electronic devices. The in-situ tungsten-incorporated homoepitaxial diamond by introducing tungsten hexacarbonyl has been proposed. A 3 × 3 × 0.5 mm³ high-pressure, high-temperature (001) diamond substrate was cut into four pieces with controlled experiments. The deposition of tungsten-incorporated diamond changed the atomic arrangement of the original diamond defects so that the propagation of internal dislocations could be inhibited. The SEM images showed that the etching pits density was significantly decreased from 2.8 × 10⁵ cm⁻² to 2.5 × 10³ cm⁻². The reduction of XRD and Raman spectroscopy FWHM proved that the double-layer tungsten-incorporated diamond has a significant effect on improving the crystal quality of diamond bulk. These results show the evident impact of in situ tungsten-incorporated growth on improving crystal quality and inhibiting the dislocations propagation of homoepitaxial diamond, which is of importance for high-quality diamond growth.

Fabrication of single crystal diamond capacitive pressure sensor is presented. Firstly, the single crystal diamond cantilever beam was formed on HPHT diamond substrate by using selective high-energy ion implantation, metal patterning, ICP etching and electrochemical etching techniques. Secondly, on this diamond cantilever beam, the desired electrode patterns were processed with photolithography and metal evaporation methods. Furthermore, the displacements of cantilever beam under different pressure conditions were investigated by atomic force microscopy. The capacitance-voltage curves of single crystal diamond cantilever beam and substrate under different force loading conditions were measured by using Agilent B1505A parameter analyzer. The results show that sensitivity increases with the enlargement of electrode area of cantilever beam, and decreases with the rise of measurement frequency.

A normally off hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field effect transistor (MOSFET) is realized by using lanthanum oxide (La₂O₃) gate dielectric. The threshold voltage is demonstrated to be −0.797 V, indicating that the La₂O₃-gated H-diamond MOSFET has normally off characteristics. The normally off mode could be greatly ascribed to the low work function of La₂O₃. Based on the capacitance–voltage (C–V) curves, the dielectric constant of La₂O₃ is calculated to be as high as 25.6. Moreover, the small hysteresis voltage extracted from the C–V curves exhibits low trapped charge density in the La₂O₃ layer. The maximum drain–source current, maximum transconductance, subthreshold swing, effective mobility, current on/off ratio, and sheet hole density of La₂O₃-gated MOSFET with a gate length of 2 μm are calculated to be −13.55 mA/mm, 4.37 mS/mm, 161 mV/dec, 202.2 cm²/V·s, 10⁸, and 6.53 × 10¹² cm⁻², respectively. This work will significantly promote the development of normally off H-diamond MOSFET devices.

Diamond Schottky barrier diodes (SBDs) could theoretically operate at high voltage, high temperature, and high frequency and be potentially used in power electronics. However, the device breaks down prematurely and cannot operate stably at high voltages due to the edge electric field crowding. In this work, a vertical diamond SBD with a curved field plate (CFP) was prepared using a chemical reflow method, inductively coupled plasma etching, and electron-beam evaporation. This structure alleviates the electric field crowding at the edge of the Schottky electrode and results in a breakdown voltage and current density of 380 V and over 3000 A/cm2, respectively. After repetitive measurements, we found that the device can repeatedly breakdown at around 380 V. These results indicate that CFP structure diamond SBDs have great application in high-voltage and high-power electronic devices.