Abstract
In this paper, we fabricated Gallium Nitride (GaN) vertical p-i-n diodes grown on free-standing GaN (FS-GaN) substrates. This homogeneous epitaxy led to thicker GaN epi-layers grown on the FS-GaN substrate, but a high crystalline quality was maintained. The vertical GaN p-i-n diode showed a low specific on-resistance of 0.85 mΩ-cm2 and high breakdown voltage (BV) of 2.98 kV. The high breakdown voltage can be attributed to the thick GaN epi-layer and corresponds to the mesa structure. Improvement of the device characteristics by the mesa structure was investigated using device simulations. We proved that a deeper mesa depth is able to decrease the electric field at the bottom of the mesa structure. Furthermore, a smaller mesa bevel angle will assist the BV up to 2.98 kV at a 60° bevel angle. Our approach demonstrates structural optimization of GaN vertical p-i-n diodes is useful to improve the device performance.
Highlights
Gallium Nitride (GaN)-based power devices have attracted much attention due to their excellent properties, such as their high breakdown electric field (~3.3 MV/cm), high power switching efficiency, and high thermal stability [1,2]
The breakdown voltage (BV) of a vertical GaN-on-GaN p-i-n diode can be enhanced through electrical field modulation by using various termination techniques such as the metal field plate structure [6] and multi-step mesa structure formed by reactive ion etching (RIE) [7]
Transmission electron microscopy (TEM), and X-ray diffraction (XRD) were analyze the parameters of GaN grown on free-standing GaN (FS-GaN) substrates
Summary
Gallium Nitride (GaN)-based power devices have attracted much attention due to their excellent properties, such as their high breakdown electric field (~3.3 MV/cm), high power switching efficiency, and high thermal stability [1,2]. Typical vertical GaN-based power devices are grown on free-standing GaN substrates. We can enhance the BV by extending the drift which means the BV the canBV be can improved by increasing the n−-region thickness. The GaN-on-GaN homogeneous epitaxy provides a way to overcome the high stress from thick epi-layers. Thicker epi-layers require deeper mesa etching depths for device isolation. The etched profile of the deep mesa is crucial to improve the BV [8] BV improvement was investigated using models of vertical GaN p-i-n diodes. We found BV was affected by the n− -layer thickness and mesa simulated models of vertical GaN p-i-n diodes. Transmission electron microscopy (TEM), and X-ray diffraction (XRD) were analyze the parameters of GaN grown on FS-GaN substrates. Employed to analyze the parameters of GaN grown on FS-GaN substrates
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