Optimization of Schottky-contact process on 4H-SiC Junction Barrier Schottky (JBS) Diodes

SiC Junction Barrier Schottky (JBS) Rectifier is a kind of unipolar power diode with low threshold voltage and high reverse blocking voltage. And the Schottky barrier Φ BN is a main technology parameter, which could greatly affect the forward conduction power and reverse leakage current in the JBS rectifiers. Therefore, it is necessary to balance the influence of Φ BN on the electrical characteristics of JBS rectifiers. In this paper, physical properties at the metal-semiconductor at the Schottky-contact could be optimized by the improvement of Schottky-contact process. And this optimization could significantly decrease Φ BN to reduce the on-state voltage drop V F and minimize negative impact on its reverse characteristics. After the completion of Silicon carbide JBS diodes, the static parameter electrical test was carried out on the wafer by using Keysight B1505A Power Device Analyzer/Curve Tracer. The test results show that the Schottky barrier height Φ BN of JBS Schottky rectifier manufactured by the modified Schottky foundation technology decreased from 1.19eV to 0.99eV and I R increased from 1.08μA to 3.73μA (reverse blocking voltage V R=1200V). It indicated that the power consumption of Schottky barrier junction in JBS rectifiers could be significantly reduced by about 25%, and I R could effectively be limited to less than 10μA.

A new structure of a wide band bridge power limiter

In this work, new design and simulation of a microstrip power limiter based on Schottky diode is presented. The proposed circuit is a zero bias power limiter built by associating a transmission line in parallel to a four Schottky rectifier bridge circuit. The first circuit using a single stage rectifier is analyzed and simulated. To improve this single stage, a second and final limiter is designed with two stages rectifier. Simulation results for the final circuit show an ideal limiter behavior and good performance of limiting rate up to 20dB for a threshold input power varying from 5 dBm to 30 dBm. While insertion loss remains low at small signal.

Surface Effects of Passivation within Mo/4H-SiC Schottky Diodes through MOS Analysis

Passivation treatments applied prior to Mo metallisation on Silicon Carbide (SiC) Schottky rectifier and metal-oxide-semiconductor capacitor (MOSCAP) structures are studied. A control sample and two treatments, comprising of an O2 oxidation and a phosphorus pentoxide (P2O5) deposition, were studied. Electrical characterisation results show that P2O5 treatment improves the homogeneity of the diodes, with the ideality factor reducing to 1.02 and the leakage current reducing by three orders of magnitude to 2×10-5 A/cm2. Furthermore, the SBH was lowered by 0.11 eV and the variance of all the P2O5 treated Schottky characteristics over the batch reduced. Characterisation by X-ray photoelectron spectroscopy (XPS) showed that the stoichiometry, the Si:C ratio, of the SiC below the contact increased from 0.93:1 before treatment to 0.97:1 after P2O5 treatment.