Analysis of Drain-Dependent Threshold Voltage and False Turn-On of Schottky-Type p-GaN Gate HEMT in Bridge-Leg Circuit

• Published in: IEEE transactions on power electronics 2024-02, Vol.39 (2), p.2351-2359
• Main Authors: Fan, Zetao, Wang, Maojun, Wei, Jin, Nuo, Muqin, Zhou, Jin, Zhang, Jiaxin, Hao, Yilong, Shen, Bo
• Format: Article
• Language: English
• Subjects: Bridge maintenance; Bridge-leg circuit; Circuit design; enhancement mode; false turn-<sc xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">on; Gallium nitrides; gate driver design consideration; HEMTs; High electron mobility transistors; High voltages; Logic gates; negative threshold voltage shift; Power semiconductor devices; Schottky diodes; Schottky-type p-GaN high-electron mobility transistors (HEMTs); Switches; Switching circuits; Threshold voltage; Transistors; Voltage measurement
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2023.3329053

To assess GaN power transistors' capability to maintain a decent enhancement-mode operation under high voltage switching operation, the impact of negative threshold voltage ( V th ) shift on false turn- on of the Schottky-type p-GaN gate high-electron mobility transistor (HEMT) is analyzed. The negative V th shift of the device at high V DS is firstly investigated by pulsed IV measurement. A customized double-pulse tester circuit is then built to evaluate the false turn- on problem. When the high-side transistor is turned on , the fast switching exerts a large overshoot current I D into the drain of the low-side device (SW2). The overshoot current consists of the displacement current that flows into C oss of the transistor and the current flowing through the channel due to false turn- on of the device. As an indicator of the false turn- on phenomenon, the peak value of overshoot current exhibits a 0.9 A difference comparing to the pure displacement current when dV/dt is 26 V/ns. The corresponding peak gate-source voltage of SW2 is 0.9 V, which is far from its 1.53 V V th . The result indicates that the negative V th shift in Schottky-type p-GaN gate HEMT aggravates the false triggering problem and special care should be taken for the design of high-voltage switching circuit.