Raman characterization of Mg⁺ion-implanted GaN

Abstract

Mg + ions were implanted at room temperature in n-type hexagonal GaN for the device isolation purposes. The implantation dose varied from 7.5 × 10 12 to 10 16 ions cm −2 . We performed resonance Raman spectroscopy and DC electrical measurements in order to monitor the structural and electrical changes of non-annealed and annealed implanted GaN samples. Annealing was carried out at 900 • C for 30 s, these conditions being used to achieve good Ohmic contacts. The aim was to determine, on the one hand, the influence of ion doses on the device isolation and, on the other, to establish the order of the technological steps which should be made between ion implantation and Ohmic contact annealing. On increasing the implantation dose from 7.5 × 10 12 to 2 × 10 14 ions cm −2 , an increase in the electrical isolation and a decrease in the photoluminescence (PL) were observed. For the highest dose, the implanted layer became conductive owing to a hopping mechanism and only the first-order phonon lines remained observable. After annealing, the implanted samples became conductive and the PL reappeared or increased compared with the nonannealed samples at same implantation doses, except for the sample implanted at the highest dose, which became insulating. Then, it is possible to achieve device electrical isolation by using a lower ion dose without thermal annealing or using a higher ion dose with thermal annealing.

Structural modifications of GaN after cerium implantation

“…Raman scattering measurements were also performed using He–Cd laser UV excitation source, line 325 nm. This excitation source gives several advantages during Raman scattering measurements of GaN over the visible laser sources . The penetration depth of this laser into GaN is calculated as 40 nm, which is much smaller than the implantation depth of 100 nm for implanted samples used in this study.…”

“…This is expected because of comparatively more lattice damage caused by heavy ion of Ce in comparison with that of Be. The strong suppression of PL emission for implanted samples is caused by the presence of defects and production of non‐radiative recombination centers emerged during high energy ion implantation . The intensity reduction provided an indirect advantage and many Raman features are observed in spectra of implanted samples.…”

Electrical Characterization and Transmission Electron Microscopy Assessment of Isolation of AlGaN/GaN High Electron Mobility Transistors with Oxygen Ion Implantation

“…Implantation isolation has been studied in pure GaN or AlGaN materials using H þ , He þ , N þ , F þ , Mg þ , Ar þ , and Zn þ ions. [2][3][4][5][6][7][8] The O þ ion implantation isolation was also investigated on AlGaAs, 9) InAlN, 10) and GaN (n-type doping)/GaN materials, 11) to study the isolation quality and P/He, Ar þ , and N þ ion implantations have been carried out in the isolation of AlGaN/GaN HEMTs. [12][13][14] In this study, multienergy O þ ion implantation was applied for isolation in the fabrication of AlGaN/GaN HEMTs.…”

Cu Induced Optical Transitions in MOCVD Grown Cu Doped GaN

“…Ion implantation has become more popular, because it is a more controlled and a precise method of doping a selective area of the sample. However, crystalline damage during the ion implantation is unavoidable, since it is a thermodynamically unstable method [3,4]. Therefore, application of in situ doping of Cu has an advantage since this process does not introduce damage to the lattice structure.…”