The world’s first 1200V silicon substrate GaN-based longitudinal power device

Gallium nitride (GaN) electronic devices have higher withstand voltage, faster switching frequency, smaller on-resistance and many other excellent characteristics, in the field of power electronic devices has a wide range of application prospects: from the low-power segment of consumer electronics, to the middle power segment of the automotive electronics field, and the high-power segment of the industrial electronics field, the current 650V GaN-based horizontal power devices (such as HEMT) have been widely used in consumer electronic products fast charging equipment, big data center power management system, The 1200 V class devices that are expected to be applied to electric vehicles are a research hotspot and difficulty in the field of GaN power electronic devices.

Figure 1. Comparison of characteristics of GaN-based longitudinal and transverse power devices

Compared with horizontal power electronic devices, GaN longitudinal power devices can provide higher power density/wafer utilization, better dynamic characteristics, and better thermal management, while large-size, low-cost silicon-substrate GaN longitudinal power electronic devices have attracted the attention of many scientific research teams at home and abroad, and important progress has been made in recent years.

Figure 2. (a) Doping concentration (SIMS data) and net carrier concentration (C-V data) of the drift layer Si affected by silane flow; (b) Effect of ion implantation protection ring on reverse electrical characteristics of the device, illustration: SEM diagram of ion implantation protection ring; (c) Evaluation system of off-state breakdown voltage and on-state resistance (Ron, sp) of GaN-based longitudinal power diodes. Comparison of the performance of GaN-based Schottky barrier diode (SBD), junction barrier Schottky diode (JBS), and groove MOS-type Schottky diode (TMBS) devices of self-supporting substrate and silicon substrate by relevant research teams at home and abroad

Sun Qian’s research team of Suzhou Institute of Nanotechnology, Chinese Academy of Sciences has successively made breakthroughs in core technologies such as doping precision regulation of drift region, device off-state electron transport mechanism and high-voltage breakdown mechanism, terminal development of high-performance ion implantation protection loop, etc., and has developed a silicon-based GaN longitudinal Schottky barrier diode with a shutdown withstand voltage of 603V and a Baliga excellent value (a comprehensive index to measure the forward and reverse electrical performance of the device) of 0.26GW/cm2. The relevant indicators are publicly reported best values for the same type of devices (IEEE Electron Device Letters, vol. 42, no. 4, pp. 473-476, Apr 2021; Applied Physics Letters, vol. 118, no. 24, 2021, Art. no. 243501; IEEE Transactions on Electron Devices, vol. 68, no. 11, pp. 5682-5686, 2021)。

Figure 3. (a) Schematic diagram of a GaN longitudinal p-n power diode on a silicon substrate; (b) Net carrier concentration distributed with depth of drift region; (c) CL-mapping plot of epitaxial materials in the drift region; (d) Forward electrical data of devices with protective loops; (e) The effect of the protection ring on the reverse electrical characteristics of the device

Building on previous work, the team recently developed a 1200 V pn power diode based on a high-quality silicon-based GaN drift region material with a thickness of 6.6 μm and a penetration dislocation density as low as 9.5 x 107 cm-3 (the lowest value among publicly reported devices). The ideal factor of the device is as low as 1.2; the device can still operate normally at a temperature of 175°C at a reverse bias voltage of 1000 V, and 10 power cycles have shown that the device has good reliability, and the dynamic on-resistance reduction affected by bias voltage and on-time has been studied, and the related operation is 1200-V GaN-on-Si Quasi-Vertical p-n Diodes Incorporated was published in IEEE Electron Device Letters 43 (12), 2057-2060 (2022), the first author is Dr. Guo Xiaolu, Special Research Assistant of Suzhou Institute of Nanotechnology, Chinese Academy of Sciences, and the corresponding author is Sun Qian and Special Research Assistant Dr. Zhong Yaozong.

Figure 4. (a) Temperature-dependent reverse electrical characteristics; (b) Dynamic on-resistance affected by reverse bias and its time-resolved plot; (c) Continuous power cycling test and (d) forward electrical characteristic curves of pre- and post-test devices

Figure 5. Evaluation system of off-state breakdown voltage and on-resistance (Ron, sp) of GaN-based longitudinal power diodes. Comparison of the performance of GaN-based Schottky barrier diode (SBD), p-n power diode (PN) and field effect transistor (FET) devices of self-supporting substrate and silicon substrate by relevant research teams at home and abroad

The above research work has been supported by the National Key R&D Program, the National Natural Science Foundation of China, the Key Frontier Scientific Research Program of the Chinese Academy of Sciences, and the Key R&D Program of Jiangsu Province. (Source: Suzhou Institute of Nanotechnology and Nanobionics, Chinese Academy of Sciences)

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