Reduction in Buffer Leakage Current with Mn-Doped GaN Buffer Layer Grown by Metal Organic Chemical Vapor Deposition

Abstract

The effect of Mn-doping into a GaN buffer layer grown by metal organic chemical vapor deposition (MOCVD) on the reduction in the leakage current of high-electron-mobility transistors (HEMTs) was investigated. Both the surface morphology and crystallinity maintained their quality even after heavy Mn-doping. The sheet resistance of GaN films increased with increasing amount of Mn-doping. The origin of semi-insulating GaN layer is considered to be electron scattering and the carrier compensation mechanism involving deep levels generated by the Mn impurity. When using the Mn-doped GaN buffer layer for the HEMT structure, the leakage current was reduced to five orders of magnitude lower than that without Mn-doping. Although Mn-doping is an effective technique for reducing the buffer leakage current, it is found that current collapse is emphasized when using the Mn-doped GaN buffer layer. We suggest that Mn atoms, which diffused to the GaN channel layer, induce the current collapse.

Raman scattering studies of the lateral Mn distribution in MBE-grown Ga1-Mn N epilayers

“…The main feature provided by this plot is that  LO decreases with x, a fact anticipated on the account of the increase of the c lattice parameter on x in (Ga,Mn)N epilayers [5][23]. This assumption is fully corroborated by the insulating character of magnetically homogeneous (Ga,Mn)N bulk crystals [47] and epilayers [28,[48][49][50], thus no influence of phonon-plasmon coupling is expected here. Now, guided by the spread of the points in Fig.…”

Electrical characteristics of vertical-geometry Schottky junction to magnetic insulator (Ga,Mn)N heteroepitaxially grown on sapphire

“…This magnetic form of GaN, in which a small percentage of Ga atoms is randomly substituted by Mn, belongs to increasingly important group of Rashba materials [3]. The established strong mid-gap Fermi-level pinning [11] [12] and the absence of a depletion layer, in combination with its insulating character [13] [14][15] [16] and a sizable dielectric strength of at least 5 MV/cm [17], points at Mn containing GaN as a worthwhile insulating buffer material for applications in (high power) nitride devices. By the same token this ferromagnetic insulator appears to be an ideal building block for nitride based spin harnessing concepts, which could further stimulate the development of all-nitride low power information processing and wireless communication technologies based on spin waves, the so called magnonics [18].…”

Two-Probe Measurements of Electron Transport in GaN:Si/(Ga,Mn)N/GaN:Si Spin Filter Structures

“…The importance of GaN-based compounds and heterostructures stems from the growing significance of wide band-gap materials in conventional electronics, particularly in opto-and high power electronics. The established a strong mid-gap Fermi-level pinning and a lack of a depletion layer, in combination with its insulating character due to a strong electron trapping by mid-gap Mn 2+ /Mn 3+ level [4,5] and a sizable dielectric strength of 5 MV/cm [6], point at (Ga,Mn)N as insulating buffer material for applications in (high power) nitride devices and make it an ideal building block for spin harnessing structures like spin filters [7] and resonant tunneling devices [8]. Besides these technologically relevant concepts, the spin imbalance in these systems may allow probing spin-orbit coupling, quantum Hall effects, and pairing in unconventional superconductors [9].…”