Trench MOS Barrier Schottky Rectifier Research Articles

Vertical GaN trench MOS barrier Schottky rectifier maintaining low leakage current at 200 °C with blocking voltage of 750 V

In this paper, we report on a vertical GaN trench MOS barrier Schottky (TMBS) rectifier for attaining low leakage current at high temperature and high reverse voltage. At 200 °C, a high blocking voltage of 750 V was achieved at a leakage current of 1 mA/cm2. To the best of our knowledge, this blocking voltage is the highest ever reported for GaN Schottky rectifiers operating at such a high temperature. Furthermore, the fabricated TMBS rectifier operated at large forward currents up to 10 A. These results verify that the developed vertical GaN TMBS rectifiers have great potential as high-power and high-temperature devices.

Fabrication and Characterization of Graphene-on-Silicon Schottky Diode for Advanced Power Electronic Design

In this study, graphene-on-silicon process technology was developed to fabricate a power rectifier Schottky diode for efficiency improvement in high operating temperature. Trench-MOS-Barrier-Schottky (TMBS) diode structure was used to enhance the device performance. The main objective of this research was to study the effect of reduced graphene oxide (RGO) deposited on silicon surface for Schottky barrier formation and heat transfer in Schottky junction. The study showed RGO deposited on silicon as a heat spreader could help to reduce the effect of heat generated in the Schottky junction that leads to a leakage current reduction and efficiency improvement in the device. With comparison to the conventional metal silicide (titanium silicide and cobalt silicide), the leakage reduced by two-orders of magnitude when tested under high operating temperature (>100°C). TMBS rectifier diode that uses graphene-based heat spreader could produce highly reliable product able to withstand high temperature operating condition.

High-voltage 4H-SiC trench MOS barrier Schottky rectifier with low forward voltage drop using enhanced sidewall layer

In this paper, a 4H-SiC trench MOS barrier Schottky (TMBS) rectifier with an enhanced sidewall layer (ESL) is proposed. The proposed structure has a high doping concentration at the trench sidewall. This high doping concentration improves both the reverse blocking and forward characteristics of the structure. The ESL–TMBS rectifier has a 7.4% lower forward voltage drop and a 24% higher breakdown voltage. However, this structure has a reverse leakage current that is approximately three times higher than that of a conventional TMBS rectifier owing to the reduction in energy barrier height. This problem is solved when ESL is used partially, since its use provides a reverse leakage current that is comparable to that of a conventional TMBS rectifier. Thus, the forward voltage drop and breakdown voltage improve without any loss in static and dynamic characteristics in the ESL–TMBS rectifier compared with the performance of a conventional TMBS rectifier.

Improved trench MOS barrier Schottky rectifier by dielectric engineering

An improved trench MOS barrier Schottky (TMBS) rectifier by dielectric engineering variable K TMBS (VK-TMBS) is proposed and studied by two-dimensional numerical simulations. The device shows increasing forward current density and reduction in specific on-resistance (R sp), as compared with a regular TMBS rectifier. VK-TMBS attains a breakdown voltage of 140 V, which is larger than that of the original TMBS. The forward voltage drop of TMBS is 0.64 V at 180 A/cm2, and that of VK-TMBS is 0.59 V. The R sp of VK-TMBS is 26.7% smaller than that of the TMBS. The numerical simulation results indicate that the proposed device features high performance with an improved figure of merit.

Trapezoid mesa와 Half Sidewall Technique을 이용한 4H-SiC Trench MOS Barrier Schottky(TMBS) Rectifier

In this study, an 4H-SiC Trench MOS Barrier Schottky (TMBS) rectifier which utilizes the trapezoid mesa structure and the upper half of the trench sidewall is proposed to improve the forward voltage drop and reverse blocking voltage concurrently. The proposed 4H-SiC TMBS rectifier reduces the forward voltage drop by 12% compared to the conventional 4H-SiC TMBS rectifier with the tilted sidewall and improves the reverse blocking voltage by 11% with adjusting the length of the upper sidewall. The Silvaco T-CAD was used to analyze the electrical characteristics.

Improvement of trench MOS barrier Schottky rectifier by using high-energy counter-doping trench-bottom implantation

A trench MOS barrier Schottky (TMBS) rectifier formed by using high-energy boron trench-bottom implantation has been proposed. As compared to the conventional TMBS rectifier, this proposed device can achieve much larger reverse blocking voltage without considerable degradation of forward characteristics. By this scheme, the large peak electric field near the trench corner can be largely reduced due to charge compensation. In addition, owing to the presence of the counter-doped region, the second peak electric field is created below the trench bottom. Higher trench-bottom implantation energy may form wider boron dopant distribution, which facilitate larger alleviation of the second peak electric field. However, too high boron implantation energy may considerably cause dopant encroachment into the mesa region, which would increase the second electric field. Hence, properly high trench-bottom implantation energy should be employed to simultaneously cause low peak electric field at regions near the trench corner and below the trench bottom, thus providing a relatively high blocking voltage for this TMBS rectifier.

Trench MOS barrier Schottky rectifier formed by counter-doping trench-bottom implantation

A trench MOS barrier Schottky (TMBS) rectifier has been formed by carrying out trench bottom counter-doping implantation for improving the blocking voltage and the device reliability. By additionally implementing a counter-doped region enclosing the trench bottom, the reverse blocking voltage of the conventional TMBS rectifier can be significantly enhanced without considerable degradation of on-state characteristics. In addition, the device reliability can be significantly improved. The large peak electric field in the corner of trench bottom, which limits the blocking voltage of the conventional TMBS rectifier, can be largely alleviated due to charge compensation. Though the counter-doped region enclosing the trench bottom may partly encroach into the mesa region, no considerable deterioration of on-state characteristics is caused. In addition, a too low-dose trench-bottom implantation cannot provide sufficient charge compensation, and a too high-dose trench-bottom implantation would create a large peak electric field below the trench bottom. As a result, a proper trench-bottom implantation may be employed to significantly enhance the blocking voltage without considerable degradation of on-state characteristics.

A fully planarized 4H-SiC trench MOS barrier Schottky (TMBS) rectifier

A fully planarized 4H-SiC trench MOS barrier Schottky (TMBS) rectifier has been designed, fabricated and characterized for the first time. The use of a TMBS structure helps improve the reverse leakage current by more than three orders of magnitude compared to that of a planar Schottky rectifier. We have achieved a low reverse leakage current density of 6/spl times/10/sup -6/ A/cm/sup 2/ and a low forward voltage drop of 1.75 V at 60 A/cm/sup 2/ for the TMBS rectifier. The static current-voltage (I-V) and switching characteristics of the TMBS rectifier have been measured at various temperatures. A barrier height of 1.0 eV and an ideality factor of 1.8 were extracted from the forward characteristics. The switching characteristics do not change with temperature indicating the essential absence of stored charge.

Design considerations and experimental analysis for silicon carbide power rectifiers

In this paper we present the investigation of properties of silicon carbide power rectifiers, in particular Schottky, PiN and advanced hybrid power rectifiers such as the trench MOS barrier Schottky rectifier. Analysis of the forward, reverse and switching experimental characteristics are presented and these silicon carbide rectifiers are compared to silicon devices. Silicon carbide Schottky rectifiers are attractive for applications requiring blocking voltage in excess of 100 V as the use of Si is precluded by its large specific on-resistance. Analysis of power dissipation indicates that silicon carbide Schottky rectifiers offer significant improvement over silicon counterparts. Silicon carbide junction rectifiers, on the other hand, are superior to silicon counterparts only for blocking voltage greater than 2000 V. Performance of acceptor (boron) and donor (phosphorus) implanted experimental silicon carbide junction rectifiers are presented and compared. Some of the recent developments in silicon carbide rectifiers have been described and compared with theory and our experimental results. The well established silicon rectifiers theory are often inadequate to describe the characteristics of the experimental silicon carbide junction rectifiers and appropriate generalization of these theories are presented. Experimental trench MOS barrier Schottky rectifiers (TMBS) have demonstrated significant improvement in leakage current compared to planar Schottky devices. Performance of current state-of-the-art silicon carbide rectifiers are far from theoretical predictions. Availability of high-quality silicon carbide crystals is crucial to successful realization of these performance projections.

Trench MOS Barrier Schottky (TMBS) rectifier: A Schottky rectifier with higher than parallel plane breakdown voltage

A new rectifier structure, called Trench MOS Barrier Schottky (TMBS) rectifier, is proposed and demonstrated by modeling and fabrication to have excellent characteristics. Two-dimensional numerical simulations have demonstrated coupling between the charge in the N − drift region and the metal on the trench sidewalls resulting in an improved electric field distribution. For epitaxial layer doping of 1 × 10 17cm −3, simulations show that break-down voltages of three times the plane parallel breakdown can be achieved with low leakage current. The measured on-state voltage drops for the devices fabricated using 0.5 μm technology at 60 and 300 A/cm 2 were 0.2 and 0.28 V, respectively. Due to smaller drift region resistances, TMBS rectifiers can be operated at large current densities (∼ 300 A/cm 2) resulting in small evice sizes.