研究目的
To investigate the performance of regrown nonpolar m-plane vertical p-n diodes, focusing on impurity incorporation at regrowth interfaces and their impact on blocking voltage, leakage currents, and other electrical characteristics, as a step toward selective-area-doped power switches.
研究成果
Regrown nonpolar m-plane p-n diodes achieve high blocking voltages up to 540 V with low specific on-resistance and ideality factors, demonstrating that interfacial impurities up to certain levels do not cause early breakdown in reverse bias but affect forward leakage. This advances the feasibility of selective-area-doped vertical power devices like JFETs and CAVETs.
研究不足
The study uses a simple etched-mesa design without edge termination structures, which may limit breakdown voltage optimization. The impact of impurities on leakage mechanisms is not fully elucidated, and further investigation is needed. The study is focused on m-plane substrates; similar studies on a-plane substrates are planned for the future.
1：Experimental Design and Method Selection:
The study involved growing p-n diodes using metal-organic chemical vapor deposition (MOCVD) on freestanding m-plane GaN substrates with a small miscut to minimize surface roughness. Various growth interruptions and regrowth conditions were employed to study impurity incorporation and diode performance.
2：Sample Selection and Data Sources:
Samples included interrupted, regrown, and continuously grown p-n diodes with drift layers of specific thickness and doping. Secondary-ion mass spectroscopy (SIMS) was used for impurity analysis, and electrical measurements were performed on fabricated devices.
3：List of Experimental Equipment and Materials:
MOCVD system for growth, freestanding m-plane GaN substrates, SIMS equipment for impurity measurement, scanning electron microscope (SEM) for imaging, electron beam-induced current (EBIC) setup, and equipment for current density-voltage (J-V) measurements.
4：Experimental Procedures and Operational Workflow:
Growth of GaN layers under specific conditions, interruptions with varying exposures, regrowth of p-GaN, fabrication of vertical p-n diodes with etched mesas, SIMS analysis of interfaces, and electrical characterization including reverse and forward J-V measurements.
5：Data Analysis Methods:
Analysis of SIMS data for impurity concentrations, extraction of electrical parameters such as blocking voltage, specific on-resistance, ideality factor, and leakage currents from J-V curves, using statistical methods for device performance comparison.
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