Observation and analysis of nine orders of magnitude memory window in pn GaN regrowth vertical diodes

Wide bandgap semiconductors, including gallium nitride (GaN), are crucial for next-generation power electronics due to their superior properties compared to silicon. However, challenges in their fabrication, particularly with epitaxial regrowth for vertical diode device structures, can introduce defects that impact performance. In this study, we report on vertical GaN pn diodes that exhibit an exceptionally large hysteresis loop with on/off ratios exceeding nine orders of magnitude, a behavior absent in devices grown in situ without changing growth reactors. We demonstrate that these devices exhibit robust endurance, maintaining a stable memory window for over 60 000 switching cycles at room temperature (20 °C), and remain partially viable up to at least 275 °C. Through analytical characterization, including secondary ion mass spectrometry and electroluminescence, we provide evidence that the hysteresis behavior is linked to a defect-rich interface region containing silicon and carbon impurities. To further investigate the underlying mechanism, we developed a technology computer aided design model that successfully replicates the observed hysteresis and identifies the likely mechanisms involved, key attributes of which include interfacial barriers, fixed negative charge, and positive charge trapping. These findings highlight a critical challenge for traditional GaN power devices while also demonstrating their potential for novel high-temperature memory applications.