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Influence of GaN- and Si?N?-Passivation Layers on the Performance of AlGaN/GaN Diodes With a Gated Edge Termination
摘要： This paper analyses the influence of the GaN and Si3N4 passivation (or 'cap') layer on the top of the AlGaN barrier layer on the performance and reliability of Schottky barrier diodes with a gated edge termination (GET-SBDs). Both GaN cap and Si3N4 cap devices show similar dc characteristics but a higher density of traps at the SiO2/GaN interface or/and an increase of the total dielectric constant in the access region result in higher RON-dispersion in GaN cap devices. The leakage current at medium/low temperatures in both types of devices shows two low-voltage-independent activation energies, suggesting thermionic and field-emission processes to be responsible for the conduction. Furthermore, a voltage-dependent activation energy in the high-temperature range occurs from low voltages in the GaN cap devices and limits their breakdown voltage (VBD). Time-dependent dielectric breakdown measurements show a tighter distribution in Si3N4 cap devices (Weibull slope β = 3.3) compared to GaN cap devices (β = 1.8). Additional measurements in plasma-enhanced atomic layer deposition (PEALD)-Si3N4 capacitors with different cap layers and TCAD simulations show an electric field distribution with a strong peak within the PEALD-Si3N4 dielectric at the GET corner, which could accelerate the formation of a percolation path and provoke the device breakdown in GaN cap SBDs even at low-stress voltages.
关键词： Si3N4 cap,GaN cap,AlGaN/GaN Schottky diode,reliability,breakdown voltage,passivation layer,off-state,Activation energy
更新于2025-09-23 15:23:52
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Real-time visualization of GaN/AlGaN high electron mobility transistor failure at off-state
摘要： Degradation and failure phenomena in high electron mobility transistors (HEMTs) are complex functions of electrical, thermal, and mechanical stresses as well as the quality of the device materials and their interfaces. Thus, it is difficult to predict or identify the dominant mechanism under various test protocols adopted in the literature. We propose that real-time visualization of the device microstructure can shift this paradigm. This is demonstrated by operating electron transparent AlGaN/GaN HEMTs inside a transmission electron microscope (TEM). Through the bright-field, diffraction, and energy dispersive spectroscopy techniques, we show that it is possible to characterize the lattice defects and diffusion of the various elements and thus monitor the micro-structural quality during the transistor failure. Off-state failure studies in the TEM clearly show the critical role of defects and interfaces that lead to punch-through mechanisms at the drain and even source sides. The 'seeing while measuring' approach presented in this study can be useful in pinpointing the dominant failure mechanisms and their fundamental origin.
关键词： GaN HEMTs,energy dispersive spectroscopy,lattice defects,transmission electron microscope,off-state failure,real-time visualization
更新于2025-09-23 15:21:01
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Trapping Effects Induced by Gate OFF-State Stress in AlGaN/GaN High-Electron-Mobility Transistors with Fe-Doped Buffer
摘要： This paper investigates the trapping characteristics in passivated Al0.23Ga0.77N/GaN High-Electron-Mobility transistors (HEMTs) with an Fe-doped buffer on Sapphire substrate. Double pulsed current–voltage (I–V ) measurements clearly exhibited the current collapse and slow detrapping transients characteristics. It is attributed to the injection of electron from gate to the traps located in the interface, the Al0.23Ga0.77N barrier and the Fe-doped buffer. By various pulse-widths of 0.5 μs, 5 μs, 10 μs, 50 μs and 0.1 ms and amplitudes of pulse-baseline (VGS-Q, VDS-Q) of ?6 V and ?8 V, we spatially analyzed the locations and corresponding detrapping time constants of the dominant traps in the device. Three different types of traps were found: a fast one with the time constant τ = 12–16 μs at the interface under gate, a middle one with τ = 0.12 ms in the AlGaN barrier layer, and a slow one in the Fe-doped GaN buffer under high reverse OFF-state stress with τ = 1.78 ms. Thus in the high voltage applications, the buffer-related deep traps are most significant.
关键词： Gate OFF-State Stress,Fe-Doped Buffer,Pulsed I–V,AlGaN/GaN HEMT,Trapping
更新于2025-09-09 09:28:46
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[Springer Theses] Electrical Properties of Indium Arsenide Nanowires and Their Field-Effect Transistors || Influence of Different Growth Methods on the Electrical Properties of InAs Nanowires
摘要： In this chapter, we have studied the similarity and difference between the electrical properties of InAs nanowires grown by two commonly used material growth systems, MBE and MOCVD. Bases on the statistical data of more than 70 InAs nanowires back-gated FETs whose diameter range from 16 nm to more than 100 nm, we ?nd that when the diameter of InAs nanowires is relatively small, most of the MOCVD-grown InAs nanowires have similar electron mobility, threshold voltage, ON-state current, and OFF-state current with MBE-grown InAs nanowires. However, the dispersion of these electrical properties within the MOCVD-grown InAs nanowires is much larger than that within the MBE-grown nanowires. On the other hand, when the diameter of InAs nanowires is relatively large, the ON-state properties of MBE- and MOCVD-grown nanowires does not show obvious difference, but their OFF-state properties have apparently different features. The MOCVD-grown nanowires have smaller OFF-state resistance than the MBE-grown nanowires, and some of the large-diameter nanowires even show metallic behavior. By simulating the distribution of electrons under ON-state and OFF-state in the nanowires with various doping levels through the ?nite element model, we attribute the background carbon doping induced by the organic sources used in the growing procedures of MOCVD to be the main cause for the above differences. Our work has deepened the understanding of the relation between nanowire growth and device performance, and may be instructive for controlling the growth of InAs nanowires.
关键词： OFF-state current,Growth methods,Simulation of the distribution of electrons,Background carbon doping,ON-state current
更新于2025-09-04 15:30:14