Advanced Measurement Techniques and Comprehensive Analysis of Trapping and Thermal Effects in GaN-Based HEMTs

Successful employment of GaN HEMT technology in industrial sectors requires an in-depth analysis of their reliability. Therefore, it is of utmost importance to understand the parasitic effects of these devices that limit the dynamic performance of GaN-based HEMTs. This presentation covers both measurement techniques and simulation analysis to address parasitic trapping and thermal effects in GaN HEMTs. My talk will be divided into two parts: The first part will be devoted to trapping investigation in GaN-based HEMT and the second section will focus on thermal aspects. Regarding the trapping aspects, we will describe and critically compare the measurement techniques, developed in XLIM lab, for the extraction of the trap signature and the trapped electron density, by drain current transient (DCT) measurement and using Low-Frequency admittance (Im(Y22), Im(Y21)) dispersion techniques. We will also examine how TCAD simulation can clarify and enlighten the location of the traps, and the mechanisms involved. From a thermal point of view, we will discuss the challenges and difficulties associated with determining the hot-spot temperature in the channel layer of the GaN HEMTs. We will illustrate this with electrical and thermoreflectance measurements. We will also discuss how simulation combined with measurement can be used to determine the maximum temperature in the device and how the temperature profile in the transistor channel is sensitive to bias points.