Isochronal annealing study of Mg-implanted p-type GaN activated by ultra-high-pressure annealing

Hirukawa, Kazufumi; Sumida, Kensuke; Sakurai, Hideki; Fujikura, Hajime; Horita, Masahiro; Otoki, Yohei; Sierakowski, Kacper; Boćkowski, Michał; Kachi, Tetsu; Suda, Jun

doi:10.35848/1882-0786/abf4f3

Cited by 18 publications

(18 citation statements)

References 36 publications

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“…15) In our previous study, we used ultra-highpressure annealing (UHPA) which was carried out under an ultra-high-pressure nitrogen gas with GaN powder (source of Ga pressure) to suppress thermal decomposition. [16][17][18][19] This technique enables us to increase annealing temperature as well as extend annealing time. We demonstrated high activation of implanted Mg as well as a low compensation ratio, using annealing at 1400 °C for 5 min in a 1 GPa nitrogen ambient.…”

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confidence: 99%

Effect of annealing time and pressure on electrical activation and surface morphology of Mg-implanted GaN annealed at 1300 °C in ultra-high-pressure nitrogen ambient

Sumida

Hirukawa

Sakurai

et al. 2021

Appl. Phys. Express

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We performed an isothermal annealing study on Mg-implanted GaN at 1300 °C in an ultra-high-pressure (1 GPa) nitrogen ambient. Annealing for more than 30 min resulted in a high acceptor activation ratio and a low compensation ratio that were comparable to those obtained with annealing at 1400 °C for 5 min. We also performed annealing at 1300 °C in a reduced nitrogen pressure of 300 MPa which makes us possible to expand the inner diameter of annealing equipment in the future. High electrical activation, similar to one obtained by annealing at 1 GPa, was successfully obtained.

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confidence: 99%

Effect of annealing time and pressure on electrical activation and surface morphology of Mg-implanted GaN annealed at 1300 °C in ultra-high-pressure nitrogen ambient

Sumida

Hirukawa

Sakurai

et al. 2021

Appl. Phys. Express

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Uedono

Sakurai

Uzuhashi

et al. 2022

Physica Status Solidi (b)

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Herein, the annealing behaviors of defects in ion‐implanted GaN are studied by positron annihilation, cathodoluminescence, scanning transmission electron microscopy, and atom probe tomography. Si or Mg ions are implanted into GaN to obtain 300 nm deep box profiles of the impurities. The samples are annealed up to 1480 °C under a N2 pressure of 1 GPa. For as‐implanted GaN, the major defect species is identified as Ga‐vacancy‐type defects. After annealing above 1000 °C, vacancy clusters are introduced, and they remain even after 1480 °C annealing. For Mg‐implanted GaN with the Mg concentration ([Mg]) ≤ 1018 cm−3, no large change in the depth distribution of Mg is observed before and after annealing at 1400 °C. For the sample with [Mg] = 1019 cm−3, however, Mg diffuses into the bulk, which is attributed to the over‐doping of Mg and their vacancy‐assisted diffusion. The Mg diffusion is suppressed, and the donor–acceptor pair emission is enhanced by sequential N‐implantation, which is attributed to the reaction between Mg and vacancies under a N‐rich condition. For the samples annealed at 1480 °C, an accumulation of Mg around dislocation loops and Mg clustering are enhanced by the N‐implantation

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“…One of the problems is high‐temperature annealing for crystal damage recovery and dopant activation after ion implantation. It should be noted that the material of GaN would be decomposed without any protection layers when the annealing temperature exceeds 800 °C under atmospheric pressure, which has severely restricted the n ‐type [ 4 ] (>1000 °C) and p ‐type [ 5 ] (>1300 °C) activation annealing temperature. According to the reversible reaction, GaN ⇄ Ga + 1/2N 2 , low N 2 gas pressure would prompt the reaction to proceed in the direction of decomposition.…”

Section: Introductionmentioning

confidence: 99%

Impact of Protective Layer Structures on High‐Temperature Annealing of GaN

Wang

Deng

et al. 2022

Physica Status Solidi (a)

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GaN decomposition at high‐temperature annealing after ion implantation is a huge hurdle to the further maturation of GaN technology. To solve this issue, this work studies the impact of different protective layer structures on high‐temperature annealing of GaN under 1200–1250 °C, including single‐layer structures and double‐layer structures. Single‐layer structures are the SiN layer grown by low‐pressure chemical vapor deposition (LPCVD) and the SiON layer by plasma‐enhanced chemical vapor deposition (PECVD). Double‐layer structures include oxides (Al2O3, SiO2, HfO2) deposited by atomic layer deposition (ALD) on top of low‐stress SiN by LPCVD or SiON grown by PECVD and epitaxial AlN by metal–organic chemical vapor deposition (MOCVD) with sputtered AlN. It is found that either SiO2 with the low‐stress SiN or AlN double capping layers was capable of completely preventing GaN decomposition in the temperature range of 1200–1250 °C. Finally, the protective layer with 20 nm Al2O3 and 300 nm low‐stress LP‐SiN is utilized in the annealing of Si‐implanted GaN high electron mobility transistor (HEMT) structure for activation. The excellent electrical performance are characterized. This work can provide valuable information on the ion implantation and high‐temperature annealing of GaN, which is critical for the further development of gold‐free ohmic contact with GaN devices.

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Isochronal annealing study of Mg-implanted p-type GaN activated by ultra-high-pressure annealing

Cited by 18 publications

References 36 publications

Effect of annealing time and pressure on electrical activation and surface morphology of Mg-implanted GaN annealed at 1300 °C in ultra-high-pressure nitrogen ambient

Effect of annealing time and pressure on electrical activation and surface morphology of Mg-implanted GaN annealed at 1300 °C in ultra-high-pressure nitrogen ambient

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

Impact of Protective Layer Structures on High‐Temperature Annealing of GaN

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