Nonalloyed ohmic contact of AlGaN/GaN HEMTs by selective area growth of single‐crystal n⁺‐GaN using plasma assisted molecular beam epitaxy

Abstract

Selective area growth (SAG) based on plasma assisted molecular beam epitaxy (PAMBE) was demonstrated to be effective to achieve low contact resistance for nonalloyed ohmic metals. An AlGaN/GaN high‐electron mobility transistor (HEMT) using SAG by PAMBE with nonalloyed ohmic metals and recessed drain/source structure exhibited a low specific contact resistance of 3.7 × 10−5 Ω cm2, high‐peak drain current of 604 mA/mm, and small gate leakage current of 3.4 µA. These results demonstrate that SAG by PAMBE produces nonalloyed HEMT with comparable or more favorable electric performance versus conventional alloyed counterpart while avoiding problems of the latter resulting from high‐temperature annealing.

High-Performance GaN Vertical p-i-n Diodes via Silicon Nitride Shadowed Selective-Area Growth and Optimized FGR- and JTE-Based Edge Termination

“…We require a selective-area processing (SAP) technique that avoids dry etching or ion implantation induced damages and defects. Our group previously reported a plasmaassisted molecular-beam epitaxy (PAMBE) enabled selectivearea growth (SAG) process, or PAMBE-SAG, which bypasses both etching and implantation damages, and achieved record low n-type ohmic contact resistance [23]- [28]. Very recently, we demonstrated smooth p-n grid structures using this methodology [29], [30].…”

A review of selective area grown recess structure for insulated-gate E-mode GaN transistors

“…The severe issue is the SAG interface contaminations or impurities which would act as donors in the SAG layer. For some special structures, such as SAG n + source/drain regions, 24) the donor-like impurities will be beneficial. But for the E-mode SAG AlGaN/GaN heterostructure transistors, the SAG interface and SAG epitaxial layers are a critical region for the devices.…”

High‐current AlGaN/GaN high electron mobility transistors achieved by selective‐area growth via plasma‐assisted molecular beam epitaxy

“…In our previous studies, we were able to realize SAG by PAMBE, achieving a record low contact resistivity of 1.8 × 10 −8 Ω cm 2 and much enhanced peak drain currents for both GaN MESFET and HEMT . We also demonstrated that unlike ion implantation, the damage‐free PAMBE‐SAG technique is able to suppress the buffer leakage current and improve the breakdown characteristics . Due to the simultaneous improvement of drain current and breakdown voltage, PAMBE‐SAG is most suited to fabricate high power transistors.…”