We have investigated the effect of hot electron stress on the electrical properties of AlGaN/GaN high electron mobility transistors (HEMTs) of hydrogen poisoning. The AlGaN/GaN HEMTs were biased at the semi-on state, and they suffered from the hot electron stress. The devices of hydrogen poisoning were degraded, while there is almost no degradation for the fresh ones. The hot electron stress leads to the significantly positive shift of threshold voltage and the notable decrease of drain-to-source current for the AlGaN/GaN HEMTs of hydrogen poisoning. For the AlGaN/GaN HEMTs of hydrogen poisoning, the trap density increases by about one order of magnitude after the hot electron stress experiment. The physical mechanism can be attributed to electrically active traps due to the dehydrogenation of passivated point defects at AlGaN surface, AlGaN barrier layer, and heterostructure interface. The results of this paper may be useful in the design and application of AlGaN/GaN HEMTs. INDEX TERMS GaN HEMT, hydrogen poisoning, hot electron stress.
In this work, a new method for failure analysis of electronic components, high speed camera, is used to investigate burnout failure location of GaN HEMTs under RF overdrive stress. Based on the high speed camera system and the RF test system, we can filter out most of the burn flashes, and clearly locate the weak parts of devices. To further explain the burnout mechanism, a long-term (100 h) RF overdrive stress experiment was carried out and the significant degradation was observed. The drain-source current decreases and the threshold voltage drifts forward. These phenomena show that the degradation of RF overdrive stress is based on hot electron effect (HEE), which is related to the electric field. Besides, Electroluminescence (EL) tests are used and the non-uniform but strong luminescence characteristics of the gate were found, which indicates the strong electric field is the main cause of burnout. We also explore the correlation between burnout and ambient temperature. It was found that the influence of ambient temperature on the burnout was limited. At last, a TCAD simulation is carried out to confirm the temperature and electric field distribution in the device when burnout. It can be found that the electric field inside the device exceeded the breakdown electric field of GaN, which further proves that the burnout caused by RF overdrive is mainly due to electric field rather than temperature.
Volumetric 3D display system (alternatively known as true 3D display system) has recently seen great progress. Powerful and functional software that can interfaces with 3D display hardware system was eagerly expected. In this paper we propose a method of generating geometry slices that can be presented on Multi-planar 3D display which will be fused in the human visual system into a 3D volume. Our main novel contribution is to use the programming language of Maya – MEL (Maya Embedded Language) to obtain geometry slices or image slices that meet the projection requirements-- including spinning screen based projection and to and fro translating screen based projection. We show that set of cross-section slices with different thickness, interval angle or distance can be split from a built mechanical component. Moreover the experiments of assembling series of geometry slices together to form a 3D spatial object can be employed to simulate the performance of Multi-planar 3D display. The latest imaging method opens up many application areas when incorporating with a Volumetric 3D display which will enhance visualization of the complex structure , better appreciate the entire 3D data and improve product design, function visualization, manufacturing preview and maintenance training.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.