Design and demonstration of nearly-ideal edge termination for GaN p–n junction using Mg-implanted field limiting rings

Abstract

A nearly-ideal edge termination for GaN p-n junctions was designed and demonstrated using Mg-ions implanted field limiting rings (FLRs). The FLRs were fabricated via the ultra-high-pressure annealing process after implanting Mg-ions into the etched n-type region outside the main p-n junction. The results of the technology computer-aided design simulation indicate that by optimizing the space and width of the rings, the breakdown voltage (BV) can be increased by over 90% of the ideal parallel plane BV (973 V). Accordingly, the fabricated diodes exhibited low leakage current and a BV of 897 V (92% of the ideal BV).

Novel Codoping Moiety to Achieve Enhanced P‐Type Doping in GaN by Ion Implantation

“…The enhanced hole concentrations evident with oxygen incorporation reveal important considerations for device design given unintentional doping during growth and future incorporation of ion implantation capabilities. multicycle rapid thermal annealing (SMRTA), [22][23][24][25][26][27][28][29][30][31][32][33][34] ultrahighpressure annealing (UHPA), [35][36][37][38][39][40][41][42][43] gyrotron annealing, [44][45][46] microwave annealing, [47] and standard rapid thermal annealing. [48][49][50] Here we have utilized ion implantation to explore p-type dopant activation enhancement using the novel codoping moiety of introducing both acceptors and donors at a 2:1 ratio for formation of ADA complexes.…”

“…While ion implantation allows precise control of dopant location, depth, concentration, and total dose, at the time, the need for annealing and subsequent difficulties did not warrant investigation. In the intervening years, ion‐implanted magnesium activation has been attempted or demonstrated in GaN as well as forming devices such as p–i–n diodes, junction barrier Schottky (JBS) diodes, and metal‐oxide‐semiconductor field effect transistors (MOSFET) via multiple annealing techniques such as symmetric multicycle rapid thermal annealing (SMRTA), [ 22–34 ] ultrahigh‐pressure annealing (UHPA), [ 35–43 ] gyrotron annealing, [ 44–46 ] microwave annealing, [ 47 ] and standard rapid thermal annealing. [ 48–50 ] Here we have utilized ion implantation to explore p‐type dopant activation enhancement using the novel codoping moiety of introducing both acceptors and donors at a 2:1 ratio for formation of ADA complexes.…”

Effect of Ultra‐High‐Pressure Annealing on Defect Reactions in Ion‐Implanted GaN Studied by Positron Annihilation

“…Recently, Sakurai and co-workers reported that the ultrahigh-pressure annealing (UHPA) process is effective for activating implanted p-type dopant (Mg). [14][15][16][17][18][19][20][21][22] In this process, Mg-implanted GaN is annealed at a high temperature (up to 1480 °C) under a high N 2 pressure (1 GPa) without forming a surface protection film on the sample. They reported that the activation rate of Mg exceeded 70% with UHPA, and the carrier mobility was close to that of epitaxial p-type GaN.…”

Substitutional diffusion of Mg into GaN from GaN/Mg mixture

“…3,10) This is because annealing at such a hightemperature easily repairs defects such as vacancy clusters and Mg-segregation defects. 9,14) Furthermore, the edge termination of the GaN p-n junction by Mg I/I and UHPA has been reported, 15,16) and UHPA has contributed to the development of GaN power devices from the fabrication of the p-GaN region to its application. However, a high-pressure process should be avoided from an industrialization standpoint, and a process that can be completed at atmospheric pressure is desired.…”