Non-uniform Mg distribution in GaN epilayers grown on mesa structures for applications in GaN power electronics

Abstract

Repeatable asymmetric resonant tunneling in AlGaN/GaN double barrier structures grown on sapphire Applied Physics Letters 114, 073503 (2019);

High Hole Concentration and Diffusion Suppression of Heavily Mg-Doped p-GaN for Application in Enhanced-Mode GaN HEMT

“…Therefore, the deep acceptors have lower efficiency to be activated to offer free holes in the valence band for conducting. Similar competition of two emissions was also discovered recently by Hanxiao Liu et al for their low-and high-Mg doping samples [18]. They attributed the two emissions at 3.25 eV and 2.9 eV to the shallow donor-to-acceptor and deep donor-to-acceptor transitions, respectively.…”

“…However, the issue Nanomaterials 2021, 11, 1766 2 of 9 of low activation efficiency for Mg-doped p-GaN/AlGaN hetero-structures on the more economic Si substrates remains. As the Mg doping increases, the deep-level emission dominates in the photoluminescence (PL) and cathodoluminescence (CL) spectra [17,18]. This implies the formation of deeper donors to compensate holes or the creation of deeper Mg acceptor levels rather than shallow acceptor levels, further resulting in the difficulty to activate holes from the deep Mg acceptors to the valence band and decrease the activation efficiency.…”

Selective Area Regrowth Produces Nonuniform Mg Doping Profiles in Nonplanar GaN p–n Junctions

“…It has recently been recognized that nonuniform dopant incorporation during nonplanar regrowth has a detrimental impact on leakage and breakdown. − A nonplanar regrowth interface includes facets with different bonding geometries, chemical reactivities, and growth rates, leading to an evolving growth interface shape and the potential for nonuniform doping profiles. For example, reduced doping in regrown p-GaN was observed near the sidewalls of UID-GaN mesa structures compared to the top and bottom of the mesa . High off-state leakage currents have been reported in vertical JFETs and associated with weak-pinch off at the vertical sidewall of the trench due to lower doping levels and carrier compensation by impurities. , Understanding the origins and extent of nonuniform doping as a function of the growth interface orientation and growth rate can therefore support the strategies to optimize nonplanar regrowth processes and by extension performance of vertical devices.…”

Design Space of GaN Vertical Trench Junction Barrier Schottky Diodes: Comprehensive Study and Analytical Modeling

“…In addition, it is not trivial to achieve uniform pn junctions at the sidewall of the etched mesas by ion implantation. A regrowth process of p-type GaN layer may be a feasible alternative way to achieve the proposed TJBS structure [31].…”

“…In addition, it is not trivial to achieve uniform pn junctions at the sidewall of the etched mesas by ion implantation. A regrowth process of p-type GaN layer may be a feasible alternative way to achieve the proposed TJBS structure [31]. The analytical model can be used for intuitively analyzing the variation of R on and calculate the forward voltage drop (V FS ) of the TJBS diodes, which can pave the way for the design of high performance TJBS diodes for a variety of applications.…”