The aim of this paper is to improve the understanding of gallium nitride (GaN) high electron mobility transistors (HEMTs) submitted to hard switching operation, with focus on the hot-electron phenomena. This is becoming a hot-topic both for the scientific community and for the industry. The analysis is carried out through a cross-comparison of three different experimental techniques: conventional Pulsed-IV characterization, a novel pulsed-drain current transient (P-DCT) method, and a custom-developed hard switching test protocol. Hard switching analysis was performed through a novel system able to test the device in hard-switching conditions with an unprecedented turn-on slew-rate of 25 V ns⁻¹ on-wafer level. This allows μs to investigate the impact of hard switching in terms of (i) locus trajectory, (ii) dissipated power, and (iii) dynamic increase. Furthermore, the accumulation of switching stress is assessed by repeating the experiment with increasing frequency, from 1 kHz to 100 kHz. The extensive cross-analysis offers a novel insight on the degradation mechanisms occurring in power GaN HEMTs. The results collected within this paper allow: (1) to evaluate the dynamic behavior under both soft- and hard-switching stress, thus differentiating off-state and semi-on-state stress; (2) to pinpoint hot-electrons as the main cause of the current collapse observed in semi-on; (3) by comparing the results obtained from P-DCT and Hard Switching Analysis we demonstrate that the hot-electron trapping is a very fast process which can happen in few ns. The related trapping and de-trapping kinetics are investigated in detail. The results described within this paper provide novel insight on the important role of hot-electrons in the dynamic increase during hard switching operations.

本文的目的是提高对硬开关操作下的氮化镓（GaN）高电子迁移率晶体管（HEMT）的理解，重点是热电子现象。这已成为科学界和行业的热门话题。该分析是通过三种不同实验技术的交叉比较进行的：常规的脉冲IV表征，新颖的脉冲漏电流瞬变（P-DCT）方法以及定制开发的硬开关测试协议。硬开关分析是通过一种新颖的系统执行的，该系统能够在硬开关条件下以前所未有的25 V ns ^-1晶圆上导通压摆率在硬开关条件下对器件进行测试。这允许μs从（i）轨迹，（ii）耗散功率和（iii）动态方面研究硬切换的影响增加。此外，通过以从1 kHz到100 kHz的递增频率重复实验来评估开关应力的累积。广泛的交叉分析为功率GaN HEMT中发生的降解机理提供了新颖的见解。本文收集的结果允许：（1）评估软开关和硬开关应力下的动态行为，从而区分断态和半导通应力；（2）查明热电子是半导通中观察到的电流崩溃的主要原因；（3）通过比较从P-DCT和硬开关分析获得的结果，我们证明了热电子俘获是一个非常快的过程，可以在几ns内发生。详细研究了相关的捕集和去捕集动力学。 在硬切换操作中增加。