Study on Thermal Transient Measurement Method and Mechanism of GaN HEMT Power Devices

A novel power semiconductor device, GaN HEMT, has the advantages of high power density and high operating frequency. Thermal problems are caused by high power operation of the device, however, there is no specific test standard for GaN HEMT thermal resistance at present. For GaN HEMT devices with high gate impedance, the method of using gate source diode to extract junction temperature is not suitable. Therefore, in this paper, we used the on-resistance of the device as the thermal parameter of this type of device, but it is found in the test that the on-resistance of the device is unstable due to the threshold voltage drift, which leads to poor repeatability of the thermal resistance test results of the same device. The addition of high temperature baking in the post test restores the threshold voltage of the device to the initial state, so as to achieve the purpose of stable and repeatable thermal resistance test results of GaN HEMT devices. In addition, this paper does an in-depth analysis of the mechanism of poor thermal resistance test repeatability for this type of device.