Large-size (1.7 × 1.7 mm2) β-Ga2O3 field-plated trench MOS-type Schottky barrier diodes with 1.2 kV breakdown voltage and 109 high on/off current ratio

We fabricated high forward and low leakage current trench MOS-type Schottky barrier diodes (MOSSBDs) in combination with a field plate on a 12 μm thick epitaxial layer grown by halide vapor phase epitaxy on β-Ga2O3 (001) substrate. The MOSSBDs, measuring 1.7 × 1.7 mm2, exhibited a forward current of 2 A (70 A cm−2) at 2 V forward voltage and a leakage current of 5.7 × 10–10 A at −1.2 kV reverse voltage (on/off current ratio of > 109) with an ideality factor of 1.05 and wafer-level specific on-resistance of 17.1 mΩ · cm2.

Simulation study for GaN-based hybrid trench MOS barrier Schottky diode with an embedded p-type NiO termination: increased forward current density and enhanced breakdown voltage

In this work, a hybrid trench MOS barrier Schottky diode (TMBS) structure is proposed to improve both the forward current density and the breakdown voltage (BV) by using TCAD simulation tools. The hybrid structure means that the conventional TMBS rectifier is combined with a p-NiO/n-GaN diode. This can modulate the lateral energy bands by removing the conduction band barriers for electrons. Thus, the improved current spreading effect and the better conductivity modulation can be obtained, leading to the increased current density. Meanwhile, the embedded p-type NiO layer can also help to reduce the electric field at Schottky contact interface and the edge of anode contact/p-NiO layer interface. Thus, the breakdown voltage can be improved remarkably. Moreover, a detailed optimization strategy for the hybrid TMBS is also analyzed by varying the p-NiO layer thickness (TNiO) and the lengths of the anode electrode that is covered on the p-NiO layer (LA).

Dark current and 1/f noise in forward biased InAs photodiodes

Dark current and low-frequency noise have been studied in forward biased InAs photodiodes within the temperature range 77…290 K. Photodiodes were fabricated by diffusion of Cd into n-InAs single crystal substrates. It has been shown that, at the temperatures >130 K, the forward current is defined by recombination of charge carriers with participation of deep states in the middle of band gap. At these temperatures, a correlation is found between forward current and 1/f noise. At lower temperatures, the forward current and noise have been analyzed within the model of inhomogeneous p-n junction caused by dislocations in the depletion region. The experimental evidence has been obtained that multiple carrier tunneling is the main transport mechanism at low temperatures, which leads to an increase in low-frequency noise.

Investigation of lateral spreading current in the 4H-SiC Schottky barrier diode chip

Lateral current spreading in the 4H-SiC Schottky barrier diode (SBD) chip is investigated. The 4H-SiC SBD chips with the same vertical parameters are simulated and fabricated. The results indicate that there is a fixed spreading resistance at on-state in current spreading region for a specific chip. The linear specific spreading resistance at the on-state is calculated to be 8.6 Ω/cm in the fabricated chips. The proportion of the lateral spreading current in total forward current (P sp) is related to anode voltage and the chip area. P sp is increased with the increase in the anode voltage during initial on-state and then tends to a stable value. The stable values of P sp of the two fabricated chips are 32% and 54%. Combined with theoretical analysis, the proportion of the terminal region and scribing trench in a whole chip (K sp) is also calculated and compared with P sp. The K sp values of the two fabricated chips are calculated to be 31.94% and 57.75%. The values of K sp and P sp are close with each other in a specific chip. The calculated K sp can be used to predict that when the chip area of SiC SBD becomes larger than 0.5 cm2, the value of P sp would be lower than 10%.

Simulation of forward current-voltage characteristics for Schottky diodes with MOS trenches

Present work is devoted to the development of a mathematical model for the forward current-voltage characteristic of Schottky diodes with a metal – oxide – semiconductor (MOS) trench structure, which takes into account the accumulation of the main carriers in silicon near the walls of the trenches at a forward bias. The proposed model considers the decrease of the series resistance of the Schottky diode drift region with an increase in the voltage at the rectifying contact due to the enrichment of silicon with electrons near the walls of the trenches. The proposed model is compared with the experimental results for Schottky diodes with a metal – oxide – semiconductor trench structure with a nominal reverse voltage of 45.0 V and a nominal forward current of 50.0 A. It is shown that the error in calculating the direct voltage value for the new model does not exceed 1.2 % in the range of direct currents from 20.0 to 50.0 A, which is 4.6–9.7 times less than the calculation error for the classical model. The results obtained can be used to develop the structure and geometry of Schottky diodes with a metal – oxide – semiconductor trench structure with required electrical parameters.

CURRENT STATE, TRENDS AND CHALLENGES OF CHINA’S DIGITAL TRADE

The digitalization of economy has a significant impact on the economic sector and on other activities. In recent years, there has been a sharp increase in the digitalization of the economy in China, primarily in such an area as digital trade. China's digital trade has grown steadily in recent years, and its share in China's trade has also increased. This article proposes the term “digital trade” and presents its characteristics. Analyze the state of the China’s digital trade, the features and main trends in the development of digital trade in goods and services. In addition, put forward current problems in the development of digital trade in China. It is concluded that digital trade in China as a whole has a positive trend, but in the future, instead of digital trade in goods, digital trade in services will become a major driving force of China's digital trade. With the development of cloud computing, cloud outsourcing and offshore services will become a new sector of digital services trade in the coming years. It was noted that China's digital trade is a driver for innovative trade growth and has an active impact on China's trade and economic activity.