Qi Xin

Bio: Qi Xin is an academic researcher from University of Electronic Science and Technology of China. The author has contributed to research in topics: Breakdown voltage & Schottky diode. The author has an hindex of 3, co-authored 5 publications receiving 20 citations.

Study on the electrical degradation of AlGaN/GaN MIS-HEMTs induced by residual stress of SiN x passivation

Abstract: In this paper, we report a new phenomenon in C-V measurement of different gate length MIS-HEMTs, which can be associated with traps character of the AlGaN/GaN interface. The analysis of DC measurement, frequency dependent capacitance-voltage measurements and simulation show that the stress from passivation layer may induce a decrease of drain output current I ds , an increase of on-resistance, serious nonlinearity of transconductance g m , and a new peak of C-V curve. The value of the peak is reduced to zero while the gate length and measure frequency are increasing to 21 μm and 1 MHz, respectively. By using conductance method, the SiN x /GaN interface traps with energy level of E C −0.42 eV to E C −0.45 eV and density of 3.2 × 10 12 ∼ 5.0 × 10 12 eV −1 cm −2 is obtained after passivation. According to the experimental and simulation results, formation of the acceptor-like traps with concentration of 3 × 10 11 cm −2 and energy level of E C −0.37 eV under the gate on AlGaN barrier side of AlGaN/GaN interface is the main reason for the degradation after the passivation.

Gallium nitride-based high electron mobility transistor

Abstract: The invention discloses a gallium nitride-based high electron mobility transistor, and belongs to the technical field of semiconductor devices According to the transistor, a transverse schottky diodewith a rectifying effect is formed between a grid electrode and a drain electrode of a conventional GaN HEMT device to be used as a voltage-resistant structure, so that the surface electric field ofa component is modulated, and the distribution of a transverse electric field is optimized, thereby achieving the purpose of improving the breakdown voltage of the device; meanwhile, the existence ofthe transverse schottky diode can also bear certain reverse voltage in a blocking state, and the grid electrode is prevented from generating too large leakage current when the grid electrode is subjected to positive voltage under the positive conducting state, so that the forward current capability of the device is guaranteed; and in addition, compared with a field plate structure, additional parasitic capacitance is not introduced, so that the working frequency and the switching speed of the device are ensured, and the reliability of the device is improved

Junction barrier Schottky diode with composite dielectric layer structure

Abstract: The invention provides a junction barrier Schottky diode with a composite dielectric layer structure, belonging to the field of power device technology. According to the junction barrier Schottky diode, composite dielectric layers that are formed by contacting high and low dielectric constants are separately arranged on outer walls of two sides of an N-type material layer, and a P-type gallium nitride region is arranged inside the N-type material layer to ensure that the distribution of a longitudinal electric field that is formed from the anode to the cathode is affected, the defect that the strength of the longitudinal electric field is greatly reduced existing in a traditional JBS device can be avoided, and meanwhile, the withstand voltage drop of the device caused by the junction edge electric field concentration effect can also be avoided, the early breakdown of the device can be prevented, and thus a high withstand voltage can be achieved on the basis of guaranteeing a small start voltage and a large conduction current. In addition, the junction barrier Schottky diode provided by the invention avoids the use of field ring structures and metal field plate structures, and thus the chip area can be reduced, the cost of the device can be reduced, and the reliability of the device can be improved.

Review of AlGaN/GaN HEMTs Based Devices

Abstract: This paper presents a review of the recent advances of the AlGaN/GaN high-electron-mobility transistors (HEMTs) based devices. The AlGaN/GaN HEMTs have attracted potential for high frequency, voltage, power, temperature, and low noise applications. This is due to the superior electrical, electronic properties, high electron velocity of the GaN. These properties include the GaN wide band gap energy, electrical, optical and structural properties. The based structures of GaN such as AlGaN/GaN are driving the interest in the research areas of GaN HEMTs. Recently, the AlGaN/GaN HEMTs have gained a great potential in radio frequency (RF) and power electronics (PE) based devices and applications. The recent aspects of the AlGaN/GaN HEMTs devices are presented and discussed. The performance of different device demonstrated based on AlGaN/GaN HEMTs are reviewed. The structural, electrical, and optical properties of these devices are also reviewed.

Simulation design of a high-breakdown-voltage p-GaN-gate GaN HEMT with a hybrid AlGaN buffer layer for power electronics applications

Abstract: We propose a novel GaN high-breakdown-voltage high-electron-mobility transistor (HB-HEMT) with a p-GaN gate and hybrid AlGaN buffer to improve the breakdown voltage and Baliga’s figure of merit. The hybrid AlGaN buffer is composed of a horizontally arranged AlaGa1−aN zone and an AlbGa1−bN zone, each having different Al compositions a and b. The proposed HB-HEMT is simulated using the Silvaco technology computer-aided design (TCAD) tool ATLAS, considering the polarization model, low-field mobility, high-field mobility, and Selberherr’s impact ionization model to simulate the direct-current (DC), breakdown, and C–V properties of the proposed HB-HEMT. The breakdown voltage of the HB-HEMT is significantly improved by introducing the hybrid AlGaN buffer structure, which can effectively modulate the electric field distributions within the channel and the buffer. A high breakdown voltage (1450 V), a low specific on-state resistance (0.47 mΩ cm2), and a high Baliga’s figure of merit (4.47 GW/cm2) are obtained at the same time with an Lgd (gate-to-drain distance) of 6 µm, a distance from the gate to the AlaGa1−aN/AlbGa1−bN interface of 4 µm, and Al compositions of a = 0.25 and b = 0.1. The simulated C–V results also reveal that the GaN HB-HEMT shows better switching characteristics than the conventional GaN HEMT with a p-GaN gate.