4H-SiC Schottky Barrier Diodes Research Articles

Suppression of Leakage Current Increase of 4H-SiC Schottky Barrier Diodes during High-Temperature Annealing by "Face-to-Face" Arrangement

Suppression of Leakage Current Increase of 4H-SiC Schottky Barrier Diodes during High-Temperature Annealing by "Face-to-Face" Arrangement

Demonstration of the first 10-kV 4H-SiC Schottky barrier diodes

This letter reports the demonstration of the first 4H-SiC Schottky barrier diode (SBD) blocking over 10 kV based on 115-μm n-type epilayers doped to 5.6 × 10/sup 14/ cm/sup -3/ through the use of a multistep junction termination extension. The blocking voltage substantially surpasses the former 4H-SiC SBD record of 4.9 kV. A current density of 48 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is achieved with a forward voltage drop of 6 V. The Schottky barrier height, ideality factor, and electron mobility for this very thick epilayer are reported. The SBD's specific-on resistance is also reported.

Analysis of High Leakage Currents in 4H-SiC Schottky Barrier Diodes Using Optical Beam-Induced Current Measurements

Analysis of High Leakage Currents in 4H-SiC Schottky Barrier Diodes Using Optical Beam-Induced Current Measurements

Epitaxial Growth and Characterization of 4H-SiC(11–20) and (03–38)

ABSTRACTHomoepitaxial growth, impurity doping, and diode fabrication on 4H-SiC(11–20) and (03–38) have been investigated. Although the efficiency of nitrogen incorporation is higher on the non-standard faces than on (0001), a low background doping concentration of 2∼3×1014 cm-3 can be achieved. On these faces, boron and aluminum are less effectively incorporated, compared to the growth on off-axis (0001). 4H-SiC(11–20) epilayers are micropipe-free, as expected. More interestingly, almost perfect micropipe closing has been realized in 4H-SiC (03–38) epitaxial growth. Ni/4H-SiC(11–20) and (03–38) Schottky barrier diodes showed promising characteritics of 3.36 kV-24 mΩcm2 and 3.28 kV–22 mΩcm2, respectively. The breakdown voltage of 4H-SiC(03–38) Schottky barrier diodes was significantly improved from 1 kV to above 2.5 kV by micropipe closing.

高速成長4H-SiCエピタキシャル単結晶膜を用いた高電圧ショットキーダイオードの開発

高速成長4H-SiCエピタキシャル単結晶膜を用いた高電圧ショットキーダイオードの開発

Microwave silicon carbide Schottky diodes

A silicon carbide (4H-SiC) Schottky barrier diode designed for high power and high frequency applications is investigated. Current and capacitance measurements show that a diode with a radius of 5 µm has a cutoff frequency of 91 GHz. A larger 4H-SiC Schottky diode with an anode radius of 50 µm is shown to handle a reverse voltage of 40 V, while having a series resistance of 2.5 Ω and a cutoff frequency of 10 GHz. Empirical formulas for the series resistance and capacitance as a function of anode radius are derived for vertical diodes with cylindrical symmetry on the specific epistructure used in this work.

Static and dynamic characterization of large-area high-current-density SiC Schottky diodes

The static and dynamic characteristics of large-area, high-voltage 4H-SiC Schottky barrier diodes are presented. With a breakdown voltage greater than 1200 V and a forward current in excess of 6 A at 2 V forward bias, these devices enable for the first time the evaluation of SiC Schottky diodes in practical switching circuits. These diodes were inserted into standard test circuits and compared to commercially available silicon devices, the results of which are reported here. Substituting SiC Schottky diodes in place of comparably rated silicon PIN diodes reduced the switching losses by a factor of four, and virtually eliminated the reverse recovery transient. These results are even more dramatic at elevated temperatures. While the switching loss in silicon diodes increases dramatically with temperature, the SiC devices remain essentially unchanged. The data presented here clearly demonstrates the distinct advantages offered by SiC Schottky rectifiers, and their emerging potential to replace silicon PIN diodes in power switching applications.

Fabrication of 3.4kV high voltage n-type 4H-SiC Schottky barrier diodes using thick epitaxial layers

ABSTRACTFabrication and evaluation of high voltage n-type 4H-SiC Schottky barrier diodes (SBDs) using 27μm thick epitaxial layers were presented. To achieve the ideal value of the breakdown voltage, various parameters of junction termination extension (JTE) were investigated. We concluded that the termination of triple rings with the concentrations of 6×1017, 3×1017, 1.5×1017cm−1 outwardly was best with the simulations. The SBDs with this termination showed the blocking voltage up to 3.4kV, which is almost the ideal value. We also investigated the distribution of leakage currents at -600V in SBDs with various diameters up to 4mm. High yield was obtained in the SBDs with the diameters below 2mm. The SBDs with high leakage currents showed the excess currents in the low forward voltage region and lots of bright spots could be observed by optical beam induced current analysis.

Effect of reactive ion etch-induced damage on the performance of 4H-SiC schottky barrier diodes

The effect of reactive ion etch (RIE) induced damage on 4H-SiC surfaces etched in fluorinated plamas has been investigated and characterized using Ni Schottky diodes and x-ray photoelectron spectroscopic surface analysis. The diodes were characterized using current-voltage, current-voltage-temperature, and capacitance-voltage measurements with near ideal forward characteristics (n=1.07) and forward current density as high as 9000 A/cm2 from the control (unetched) devices. High current handling capability was observed in diodes with etched surfaces as well. Diodes with surfaces etched in CHF3 containing plasmas showed a significant reduction in the barrier height compared to the diodes with surfaces etched in CF4 containing plasma. Control devices exhibited high leakages when reverse biased, which is attributed to the presence of a thin (∼2 nm) oxide layer at the metal-semiconductor interface. However, under reverse bias diodes with CHF3-etched surfaces showed improvement in leakage current compared to diodes with CF4-etched surfaces and the control diodes.

Effect of Surface Preparation and Thermal Anneal on Electrical Characteristics of 4H-SiC Schottky Barrier Diodes

The effect of surface preparation and thermal anneal on electrical characteristics of 4H-SiC Schottky barrier diodes was investigated with the aim of finding a suitable fabrication process that would produce low reverse leakage current and low forward voltage drop. Schottky barrier diodes were fabricated on 4H-SiC surfaces using different surface preparation techniques. After fabrication, the diodes were subjected to anneal temperatures of up to 500 C. It was found that surface preparation plays a crucial role in determining the electrical characteristics of as-deposited Schottky barrier diodes. The effect of thermal anneal was (a) a reduction in leakage current by several orders-of-magnitude, (b) an increase in barrier height, (c) an improvement in ideality factor. This study suggests that the choice of surface preparation technique and anneal temperature has significant effect on the performance of 4H-SiC Schottky barrier diodes. (orig.) 6 refs.

Silicon carbide high-power devices

In recent years, silicon carbide has received increased attention because of its potential for high-power devices. The unique material properties of SiC, high electric breakdown field, high saturated electron drift velocity, and high thermal conductivity are what give this material its tremendous potential in the power device arena. 4H-SiC Schottky barrier diodes (1400 V) with forward current densities over 700 A/cm/sup 2/ at 2 V have been demonstrated. Packaged SITs have produced 57 W of output power at 500 MHz, SiC UMOSFETs (1200 V) are projected to have 15 times the current density of Si IGBTs (1200 V). Submicron gate length 4H-SiC MESFETs have achieved f/sub max/=32 GHz, f/sub T/=14.0 GHz, and power density=2.8 W/mm @ 1.8 GHz. The performances of a wide variety of SiC devices are compared to that of similar Si and GaAs devices and to theoretically expected results.

High performance of high-voltage 4H-SiC Schottky barrier diodes

High performance of high-voltage rectifiers could be realized utilizing 4H-SiC Schottky barrier diodes. A typical specific on-resistance (R/sub on/) of these devices was 1.4/spl times/10/sup 3/ /spl Omega/ cm/sup 3/ at 24/spl deg/C (room temperature) with breakdown voltages as high as 800 V. These devices based on 4H-SiC had R/sub on/'s lower than 6H-SiC based high-power rectifiers with the same breakdown voltage. As for Schottky contact metals, Au, Ni, and Ti were employed in this study. The barrier heights of these metals for 4H-SiC were determined by the analysis of current-voltage characteristics, and the reduction of power loss could be achieved by controlling the barrier heights.