Can be applied to photodetectors! China has made another important progress in this field of technology

At the world's top semiconductor and electronic device technology forum IEEE IEDM held recently, two research papers on gallium oxide devices by Professor Long Shibing's research group of the National Exemplary School of Microelectronics of China University of Science and Technology "High-power gallium oxide Schottky diode" and "gallium oxide photodetector" were successfully accepted by the conference.

Among them, in terms of gallium oxide photodetector, Professor Long Shibing's team realized the opposing grating (OPG) regulation scheme by introducing additional auxiliary light source, which alleviated the constraint relationship between the two indicators of photodetector responsiveness and response speed.

According to reports, the OPG scheme can effectively suppress the serious continuous photoconductivity effect in the device, and the response speed of the device is significantly improved, and the Ga2O3/WSe2 junction field effect transistor detector under this scheme shows a negative grating effect (NPG) under the target light (deep ultraviolet) irradiation, and the threshold voltage of the device moves in the negative direction; In contrast, the illumination of the auxiliary light source (visible light) causes the device to exhibit a forward grating effect (PPG), and the threshold voltage of the device moves in the forward direction; Under the simultaneous illumination of the target light and the auxiliary light, the device integrates positive and negative opposing grating effects, but the overall manifestation is that the threshold voltage moves in the negative direction.

At the same time, the auxiliary visible light introduced in the OPG regulation scheme has little effect on key indicators such as the light/dark current ratio and responsivity of the device. Finally, when the visible light in the OPG scheme is normally open, the response speed of > 1200 times is improved by 1200 times without sacrificing 10.4% of the responsiveness, which successfully weakens the constraint between responsiveness and response speed. When the auxiliary light source is controlled by the feedback circuit and only triggered on the falling edge of the device response, the response speed will be increased by orders of magnitude in the case of no responsiveness sacrifice, which has important reference significance for the improvement of the comprehensive performance of the photoelectric detection chip.

It is reported that gallium oxide (GaO) single crystal material is the fourth generation of wide bandgap semiconductor materials after Si, SiC and GaN, and there are 6 known crystal phases, including 5 stable phases such as α, β, γ and 1 transient phase κ-GaO, of which the β phase is a thermodynamically stable phase. Compared with SiC and GaN, gallium oxide-based power devices have the characteristics of high withstand voltage, low loss, high efficiency and small size. Gallium oxide is easier to make than SiC and GaN because of its substrate fabrication, and because of its ultra-wide bandgap characteristics, the material can withstand higher voltage collapse voltage and critical electric field, making it very promising in the application of ultra-high power components.

Gallium oxide was previously used in optoelectronic applications, and until 2012, 80% of the world's research units turned their research direction to the field of power devices.

From the market point of view, gallium oxide has just entered the initial commercial application stage from the research and development stage, the United States, Japan, Europe, South Korea, Chinese mainland and Taiwan are all developing gallium oxide wafers and devices, of which Kyma Technology (Kyma) in the United States, FLOSFIA AT KYOTO UNIVERSITY IN JAPAN AND NOVEL CRYSTAL (NOVEL CRYSTAL) are the market leaders.

In China, at present, the domestic GaO industry chain is very weak, the number of available foundries is zero, there are several epitaxial enterprises and substrate enterprises, but the scale is very small and has not yet formed mass production. Atecom Technology, a Taiwanese manufacturer and seller of silicon ingots and wafers, also deals in gallium oxide. In Chinese mainland, PAM-XIAMEN Advanced Materials is in the early stages of developing the technology.

Under this circumstance, in order to promote the development of the domestic gallium oxide industry, the Ministry of Science and Technology of China listed gallium oxide in the "14th Five-Year Key Research and Development Plan" this year, with the 46 institutes of CETC, Shandong University, Shenzhen Evolution Semiconductor, Shanghai Institute of Optics and Mechanics of the Chinese Academy of Sciences, Beijing Gallium Science and Technology, Hangzhou Fujia Gallium Industry and other units as the main force to overcome the problem of gallium oxide materials, so that the fourth generation of semiconductors has gained more extensive attention.

It is worth noting that on May 10, the Hangzhou Science and Technology Innovation Center of Zhejiang University successfully prepared 2-inch (50.8 mm) gallium oxide wafers for the first time using a new technology route, and the use of this 2-inch gallium oxide wafer with completely independent intellectual property rights technology is the first time in the world.

On December 9th, Beijing Mingjia Semiconductor Co., Ltd. successfully prepared high-quality 4-inch (001) gallium oxide (β-Ga2O3) single crystal on the main surface using the guide mode method, completed a breakthrough in 4-inch gallium oxide wafer substrate technology, and carried out multiple repeatable experiments, becoming the first industrialization company in China to master the growth technology of 4-inch (001) phase single crystal substrate of the fourth generation semiconductor gallium oxide material. The company also completed a series A financing of nearly 100 million yuan on June 30, which will be mainly used for the expansion and research and development of gallium oxide projects, and is expected to build the first complete industrial line of gallium oxide integrating crystal growth, crystal processing and film epitaxy in China by the end of 2023.

For the future of gallium oxide, Hao Yue, an academician of the Chinese Academy of Sciences, said that gallium oxide materials are one of the most likely materials to shine in the future, and in the next 10 years or so, gallium oxide devices may become competitive power electronic devices and will directly compete with silicon carbide devices. The industry generally believes that gallium oxide is expected to replace silicon carbide and gallium nitride as a representative of a new generation of semiconductor materials. At present, semiconductor companies in various countries are scrambling to layout, and gallium oxide is gradually becoming a rising star in the semiconductor material industry.