Jiangfeng Du

Bio: Jiangfeng Du is an academic researcher from University of Electronic Science and Technology of China. The author has contributed to research in topics: Breakdown voltage & Barrier layer. The author has an hindex of 7, co-authored 57 publications receiving 170 citations. Previous affiliations of Jiangfeng Du include University of Sheffield.

High breakdown voltage AlGaN/GaN HEMT with high-K/low-K compound passivation

Abstract: A novel high breakdown voltage (BV) AlGaN/GaN high-electron mobility transistor (HEMT) with a high-K/low-K compound passivation layer is proposed. The compound passivation layer is formed by blocks of low-K dielectric (Si3N4) embedded in a high-K passivation layer (La2O3). Owing to their different dielectric constants, there is a discontinuity of the horizontal electrical field at the high-K/low-K interface, which can introduce a new electric field peak in the nearby channel in the semiconductor and can also modulate the distribution of the electric field along the channel. Hence, enhancement of BV can be achieved. Compared to the typical field-plate structure, high-K/low-K passivation introduces no parasitic capacitance. On the basis of the physical mechanism, several design principles for the high-K/low-K passivation layer are presented. Numerical simulation demonstrates a BV of 1400 V for the proposed device with four blocks of low-K dielectric embedded in a high-K passivation, compared to the BVs of 917 and 288 V for the device with high-K passivation and the device with low-K passivation, respectively.

Study on transconductance non-linearity of AlGaN/GaN HEMTs considering acceptor-like traps in barrier layer under the gate

Abstract: DC and pulsed transfer characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) have been systematically investigated. A significant difference of transconductance linearity between DC and gate-pulsed measurements is clearly observed. The acceptor-like traps in the barrier layer under the gate is the main cause of non-linear behavior of AlGaN/GaN HEMTs transconductance. A physical model has been constructed to explain the phenomenon. In the modeling, an acceptor-like trap concentration of 1.2 × 1019 cm−3 with an energy level of 0.5 eV below the conduction band minimum shows the best fit to measurement results.

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.

Simulation and characterization of millimeter-wave InAlN/GaN high electron mobility transistors using Lombardi mobility model

Abstract: A gate length of 0.2 μm InAlN/GaN high electron mobility transistor on SiC substrate is obtained with a maximum current gain cutoff frequency (fT) of 65.8 GHz and a maximum power gain cutoff frequency (fmax) of 143.6 GHz. Lombardi model, which takes interface roughness scattering into consideration, has been introduced to model the transconductance (gm) degradation. The simulated gm and fT with Lombardi model are 69% and 58% lower than the ones without considering interface roughness scattering, respectively. Further analysis show experimental gm, gate capacitance (Cg), and fT are consistent with results based on Lombardi model.

GaN Technology for Power Electronic Applications: A Review

Abstract: Power semiconductor devices based on silicon (Si) are quickly approaching their limits, set by fundamental material properties. In order to address these limitations, new materials for use in devices must be investigated. Wide bandgap materials, such as silicon carbide (SiC) and gallium nitride (GaN) have suitable properties for power electronic applications; however, fabrication of practical devices from these materials may be challenging. SiC technology has matured to point of commercialized devices, whereas GaN requires further research to realize full material potential. This review covers fundamental material properties of GaN as they relate to Si and SiC. This is followed by a discussion of the contemporary issues involved with bulk GaN substrates and their fabrication and a brief overview of how devices are fabricated, both on native GaN substrate material and non-native substrate material. An overview of current device structures, which are being analyzed for use in power switching applications, is then provided; both vertical and lateral device structures are considered. Finally, a brief discussion of prototypes currently employing GaN devices is given.

Enhancing Performance of a GaAs/AlGaAs/GaAs Nanowire Photodetector Based on the Two-Dimensional Electron–Hole Tube Structure

Abstract: Here, we design and engineer an axially asymmetric GaAs/AlGaAs/GaAs (G/A/G) nanowire (NW) photodetector that operates efficiently at room temperature. Based on the I-type band structure, the device...

Electronics and Packaging Intended for Emerging Harsh Environment Applications: A Review

Abstract: Several industrial applications require specific electronic systems installed in harsh environments to perform measurements, monitoring, and control tasks such as in space exploration, aerospace missions, automotive industries, down-hole oil and gas industry, and geothermal power plants. The extreme environment could be surrounding high-, low-, and wide-range temperature, intense radiation, or even a combination of above conditions. We review, in this paper, the main leading applications that demand advanced technologies to fit the unconventional requirements of extreme operating conditions, discussing their main merits and limits compared to established and emerging technologies in this field, including silicon (Si), silicon on insulator (SOI), silicon germanium (SiGe), silicon carbide (SiC) as well as III–V semiconductors particularly the gallium nitride (GaN) semiconductor. In spite of successfully exceeding extreme conditions borders by developing advanced semiconductor devices dedicated for harsh environments, especially in high-temperature applications, the packaging challenges are still limiting the reliability of the developed technologies. Those challenges are examined in this review in terms of limitations and proposed solutions.