Interactive human-machine interfaces are developed using ultrathin, stretchable, multifunctional metal oxide electronics.

In this work, details of stress time dependent transient ${V}_{\text {T}}$ shift in p-GaN Gate HEMTs are captured using a fast sweeping method. A minimum saturated ${V}_{\text {T}}$ shift ( $\Delta {V}_{\text {T}\_{}\text {Sat}}$ ) independent of stress time at about 4 V gate stress is observed, and electron tunneling process assisted by shallow traps in the AlGaN barrier is introduced as a likely mechanism to explain the phenomena. Under gate stress of 6 V and above, a stress time dependent over-recovery results in a negative ${V}_{\text {T}}$ shift before the final recovery to the fresh state, confirming that hole de-trapping process needs to take a longer time than electron de-trapping process. In addition, under AC gate stress condition, $\Delta {V}_{\text {T}\_{}\text {Sat}}$ shows an opposite trend in cases of low and high forward AC gate bias stresses, which is explained by the difference in the trapping rates of electrons and holes.

A double-diode-isolation method with low parasitic capacitance devices and reverse clamping is proposed to accurately extract the high-frequency and high-voltage dynamic on-resistance ( $R_{\mathrm{ dson}}$ ) of AlGaN/GaN high electron mobility transistor (HEMT) power devices. The response time required for the drain voltage to drop back to the on-voltage of this testing circuit can reach 100 ns, and the forward voltage drop of the isolation diode is monitored in real time using low-voltage probes. A low value constant current source is built to power the testing circuit at only several mA to avoid additional self-heating effect. With these improvements, we can obtain a test frequency of more than 1 MHz, a test voltage of more than 600 V and an accuracy of higher than 97.8% for the extraction of dynamic $\text{R}_{\mathrm{ dson}}$ .

In this work, temperature-dependent transient threshold voltage (V_T) instability behaviors in p-GaN/AlGaN/GaN HEMTs, with both Schottky gate (SG) and Ohmic gate (OG), were investigated systematically, under negative gate bias stress, by a fast voltage sweeping method. For SG devices, a concave-shaped V_T evolution gradually occurs with the increase in temperature, and the concave peak appears faster with increasing reverse bias stress, followed by a corresponding convex-shaped V_T recovery process. In contrast, the concave-shaped V_T evolution for OG devices that occurred at room temperature gradually disappears in the opposite shifting direction with the increasing temperature, but the corresponding convex-shaped V_T recovery process is not observed, substituted, instead, with a quick and monotonic recovery process to the initial state. To explain these interesting and different phenomena, we proposed physical mechanisms of time and temperature-dependent hole trapping, releasing, and transport, in terms of the discrepancies in barrier height and space charge region, at the metal/p-GaN junction between SG and OG HEMTs.

Radiation-hardened semiconductor GaN has drawn considerable attention owing to its excellent properties such as large displacement energy. Many studies have focused on evaluating the degradation of GaN-based power device performance by proton beam or particle irradiation, while quantitative analysis of the energy transfer process of particles inside the material and the mechanisms involved in inducing degradation of electrical properties are rare. Here, on the basis of the fabricated alpha-particle detector, a device model validated by basic electrical experiments is established to simulate the influence of alpha-particle irradiation on the leakage current of the device. We observe that the current does not change significantly with increasing radiation fluence at low bias, while it shows a descending trend with increasing radiation fluence at higher bias. However, increasing the energy of the radiation particles at the same radiation fluence directly leads to a monotonically elevated leakage current. Such a series of phenomena is associated with radiation-induced changes in the density of trapped states within the active layers of the device.