Microelectronics has developed an internationally advanced GaN-enhanced MIS-HEMT device
Recently, the GaN power electronic device research team of the Institute of Microelectronics of the Chinese Academy of Sciences teamed up with Professor Chen Jing of the Hong Kong University of Science and Technology, a professor of Xidian University and a member of the Chinese Academy of Sciences Hao Yue team to develop a GaN-enhanced MIS-HEMT device. New progress was made in the area and a high-frequency enhanced GaN MIS-HEMT device with advanced international standards was successfully developed.
The third-generation semiconductor material gallium nitride has excellent physical properties such as high forbidden band width, high breakdown electric field, high saturation electron drift velocity, and especially strong spontaneous and piezoelectric polarization effects of the material itself in AlGaN/GaN heterogeneity. The structure induces high-density, high-mobility two-dimensional electron gas (mobility up to 2000 cm2/V·s or more), which breaks through the material limits of traditional Si-based power devices. These excellent properties have made GaN power electronic devices stand out in terms of operating frequency and power conversion efficiency, making them one of the best candidates for next-generation energy-efficient power electronic devices.
Enhanced, also known as normally-off, is a key requirement for power electronics applications, where the gate trench etching process is one of the first technologies to implement GaN-enhanced devices. The traditional etching process is mainly performed at room temperature, and the in-situ recovery of the lattice damage caused by the etching and the prompt removal of the etching residue can not be achieved, resulting in a drastic reduction in the output current of the device, which becomes a constraint on the technology in GaN power electronics. Domain application bottlenecks. The research team of GaN power electronic devices of the Microelectronics Institute adopted the high-temperature etching mask technology to innovatively adopt the high-temperature gate trench etching process to significantly reduce the damage to the two-dimensional electron gas channel and increase the volatilization of the etching residue. At the same time, the independently developed ozone-assisted atomic layer deposition technology was used to prepare Al2O3 gate dielectrics with high insulation and low defects, which effectively suppressed the gate leakage current. Combining the above two innovations (as shown in Figure 1), the final developed threshold voltage +1.6V, pulse output current up to 1.13A/mm, off-state power consumption of only 6 × 10-8 W/mm GaN enhanced MIS -HEMT device. Compared to the ambient temperature etched MIS-HEMT device (output current 0.42 A/mm), the high-temperature etching output current increased nearly twice (as shown in Figs. 2(a) and (b)).
The enhanced MIS-HEMT device has a pulse output power of 5.76 W/mm at 4GHz and a power-added efficiency of 57%, which is higher than the internationally reported threshold voltage exceeding the power performance of a +1.5V MIS-HEMT device (Figure 2). c) shown). The successful development of the enhanced GaN MIS-HEMT has broken through the bottleneck of the gate trench etching technology to produce GaN power electronic devices, laying a solid foundation for further improving the operating frequency (above 10 MHz) and conversion efficiency of the gallium nitride electronic devices.
The project was funded by the National Natural Science Foundation and the Hong Kong Government’s Innovation Technology Fund. The research results are reported on Semiconductor TODAY, an authoritative website for semiconductor research, and will be published in the August Electro Electron Device Letters in August 2015.
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