Sihao Chen

Bio: Sihao Chen is an academic researcher from Shandong University. The author has contributed to research in topics: Breakdown voltage & Trench. The author has co-authored 1 publications.

Systematic Design and Parametric Analysis of GaN Vertical Trench MOS Barrier Schottky Diode With p-GaN Shielding Rings

Abstract: We report GaN vertical trench MOS barrier Schottky (TMBS) diodes with embedded p-GaN shielding rings (SRs) and systematically investigate the impact of different structural parameters of the p-GaN SRs on the breakdown performance of the GaN-based vertical TMBS diodes by numerical simulation. The charge coupling effect by the embedded p-n junction at the bottom of the trench homogenize the electric field at the trench corner and alleviate the electric field crowding effect at the Schottky contact region, which can effectively avoid the premature breakdown and improve the reverse blocking capability of the TMBS diodes. The p-GaN SRs can also broaden the overlapped depletion region and shift the pinch-off point into the n−-GaN drift region, thus facilitating the 2-D depletion in the n−-GaN drift layer and boosting the breakdown performance of the conventional TMBS diodes. We found that the doping concentration, thickness, and the width of the p-GaN SRs are closely associated with the electric field distribution and the reverse breakdown characteristics of the GaN-based vertical TMBS diodes. The vertical TMBS diodes with optimal p-GaN SR parameters featured a dramatic improvement in the breakdown voltage from 907 to 1281 V, without an obvious degradation in the ON performance. The proposed TMBS diodes with a p-GaN SR structure can pave the way toward a high-performance GaN vertical power device for high-power and high-efficiency power switch applications.

Design Space of GaN Vertical Trench Junction Barrier Schottky Diodes: Comprehensive Study and Analytical Modeling

Abstract: We report gallium nitride (GaN) vertical trench junction barrier Schottky (TJBS) diodes and systematically analyzed the effects of the key design parameters on the reverse and forward characteristics of the devices. By taking advantage of the shielding effects from both the trenches and pn junctions in the TJBS structure, the high electric field at the Schottky contact region can be effectively suppressed. We found that the doping concentration, thickness, and spacing of p-GaN, as well as the depth and angle of the trench sidewalls are closely associated with the electric field distribution and the reverse characteristics of the TJBS diodes. With an optimal set of design parameters, the local electric field crowding at either the corner of the trench or the edge of the p-GaN can also be alleviated, resulting in a boosted breakdown voltage of up to 1250 V in the TJBS diodes. In addition, an analytical model was developed to explore the physical mechanism behind the forward conduction behaviors. We believe that the results can provide a systematical design strategy for the development of low-loss, high-voltage, and high-power GaN power diodes towards an efficient power system.

Analytical Model and Design Strategy for GaN Vertical Floating Island Schottky Diodes

Abstract: We report GaN-based vertical Schottky barrier diodes (SBDs) with embedded floating islands (FIs). The incorporation of FI structure can break the theoretical limit of unipolar vertical GaN devices by homogenizing the electric field distribution within the drift layer. To facilitate comprehensive understanding and structural design of FI SBDs, analytical models for both conducting state and blocking state of GaN FI SBDs are established and verified by TCAD simulation. Parametric optimization for the reverse characteristics of GaN FI SBDs is also carried out systematically. We found that the doping concentration, height of p-GaN FIs, and spacing between adjacent p-GaN FIs are closely associated with the electric field distribution and the reverse breakdown characteristics of vertical FI SBDs. An optimum Baliga’s figure of merit (FOM) of 4.98 GW/cm2 can be achieved, which features a 79.14% enhancement compared with the conventional SBD. The results can provide systematic design guidelines for GaN vertical power electronic systems toward high-voltage, high-speed, and high-power applications.

Design optimization of high breakdown voltage vertical GaN junction barrier Schottky diode with high-K/low-K compound dielectric structure

Abstract: A vertical junction barrier Schottky diode with a high-K/low-K compound dielectric structure is proposed and optimized to achieve a high breakdown voltage (BV). There is a discontinuity of the electric field at the interface of high-K and low-K layers due to the different dielectric constants of high-K and low-K dielectric layers. A new electric field peak is introduced in the n-type drift region of junction barrier Schottky diode (JBS), so the distribution of electric field in JBS becomes more uniform. At the same time, the effect of electric-power line concentration at the p–n junction interface is suppressed due to the effects of the high-K dielectric layer and an enhancement of breakdown voltage can be achieved. Numerical simulations demonstrate that GaN JBS with a specific on-resistance (R on,sp) of 2.07 mΩ⋅cm2 and a BV of 4171 V which is 167% higher than the breakdown voltage of the common structure, resulting in a high figure-of-merit (FOM) of 8.6 GW/cm2, and a low turn-on voltage of 0.6 V.

Design Optimization of High Breakdown Voltage Vertical GaN Junction Barrier Schottky Diode with High-K/Low-K Compound Dielectric Structure

Abstract: A vertical junction barrier Schottky diode with a high-K/low-K compound dielectric structure is proposed and optimized to achieve a high breakdown voltage (BV). There is a discontinuity of the electric field at the interface of high-K and low-K layers due to the different dielectric constants of high-K and low-K dielectric layers. A new electric field peak is introduced in the n-type drift region of junction barrier Schottky diode (JBS), so the distribution of electric field in JBS becomes more uniform. At the same time, the effect of electric-power line concentration at the p-n junction interface is suppressed due to the effects of the high-K dielectric layer and an enhancement of breakdown voltage can be achieved. Numerical simulations demonstrate that GaN JBS with a specific on-resistance (R on, sp ) of 2.07 mΩ·cm2 and a BV of 4171 V which is 167% higher than the breakdown voltage of the common structure, resulting in a high figure-of-merit (FOM) of 8.6 GW/cm2, and a low turn-on voltage of 0.6 V.

Comprehensive Design and Numerical Study of GaN Vertical MPS Diodes Towards Alleviated Electric Field Crowding and Efficient Carrier Injection

Abstract: In recent years, gallium nitride (GaN) has exhibited tremendous potential for power electronic devices owing to its wider energy band gap, higher breakdown electric field, and higher carrier mobility [1]–[4]. Thanks to the availability of low-dislocation-density bulk GaN substrates and the intrinsic advantages of the vertical device topology, GaN-based vertical SBDs have been developed extensively towards high voltage and high current applications [5]–[7]. However, similar to the lateral GaN SBDs based on the AlGaN/GaN heterostructures, GaN vertical SBDs also suffer from reverse leakage issues due to the energy barrier lowering effect at high reverse bias condition. To achieve a decent device performance, several device architectures have been developed, such as junction barrier Schottky (JBS) diode [8], MPS diode [9]–[12], and trench metal-insulator-semiconductor barrier Schottky (TMBS) diode [13], [14], which are designed to move the peak electric field from the interface of the Schottky junction to the inside of the device at high reverse bias, leading to a higher breakdown voltage and a lower reverse leakage current.