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The 1.7 kV 4H-SiC MOSFET which features optimized retrograded-profile ion implantation in the JFET regions (RG-MOS) is proposed and fabricated on the 4 inch wafers. The measured results quantify the benefits of the RG-MOS structure: simultaneous improvement in high-frequency figures of merit (HF-FOM) (R on× C GD) by 1.5×, HF-FOM (R on × Q GD) by 1.5× and Baliga figure of merit (BFOM = 4BV2/ R on,sp) by 1.6× compared with the conventional MOSFET (CON-MOS). Unlike other reported complicated structures which need high-precise fabricating process, the proposed RG-MOS structure is compatible with the prior planar 4H-SiC MOSFET process, and is favorable for large-scale production. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) films have been deposited on AlGaN/GaN heterostructure substrates by plasma enhanced atomic layer deposition (PEALD). Different annealing treatments were adopted to change film structure and improve performance. Chemical composition, crystallinity, and electrical properties were studied for AlN films. The results show that some crystal grains appear in the films after annealing at a temperature of over 800 °C. The film crystalline quality increases as the annealing temperature rises. The N-O-Al bond decomposes during the high temperature annealing in N2, and some new N-Al bonds are formed in the AlN films. Annealing promotes the elemental interdiffusion between the films and the substrates. High-temperature annealing at 1000 °C in a nitrogen atmosphere can effectively promote complete nitridation of the AlN film, reduce the nitrogen vacancies, and cause the AlN film to form a semiconductor-like structure.

In this work, the interfacial modification of the ALD-SiO2/4H-SiC heterojunction with synergistic nitrogen–oxygen-atmosphere (N2/O2) rapid thermal annealing (RTA) and its physical mechanism have been systematically studied. Atomic layer deposition (ALD) can effectively suppress the carbon clusters generation at the SiO2/4H-SiC heterojunction interface and RTA in the synergistic N2/O2 can further reduce the interface states density, the near-interface-oxide-trap (NIOT) density and the leakage current. Oxygen can repair carbon-related defects, and nitrogen helps passivate carbon-related traps and dangling bonds. The synergistic N2/O2 RTA can enhance the interfacial passivation efficiency by converting sp3 carbon clusters into sp2 phases. These demonstrate that the proposed synergistic N2/O2 RTA associated with SiO2 deposition by ALD is a potential way to substitute the conventional toxic nitrous oxides annealing and high-budget thermal oxidation, which promotes the property and reliability of SiC devices. [ABSTRACT FROM AUTHOR]

The carbon clusters and oxygen vacancies-induced interface traps and near-interface-oxide traps (NIOTs) at the dielectric oxide/SiC heterojunction severely degenerate the electrical properties and reliability of SiC devices. In this work, plasma-enhanced atomic layer deposition (PEALD) is performed to deposit Al2O3 dielectrics on 4H-SiC substrate to minimize the carbon cluster formation and in situ NH3-plasma pre-treatment is utilized to further improve the interfacial properties. Significantly enhanced electrical properties of the 4H-SiC/Al2O3 heterojunction is obtained with a reduced C–V hysteresis (from 0.411 V to 0.103 V) and leakage current density (from 10–3 to 10–6 A/cm2), lowered interface states (from (5.97–8.63) × 1011 to (4.10–7.56) × 1011 eV−1 cm−2) and NIOTs (from (6.15–6.82) × 1012 to (4.26–4.53) × 1011 eV−1 cm−2) and improved dielectric breakdown electric field (from 7.68 to 8.75 MV/cm). This demonstrates that in situ NH3-plasma pre-treatment associated with high-κ dielectrics is a promising technique for future high-power device applications. [ABSTRACT FROM AUTHOR]