Control of plasma-CVD SiO 2 /InAlN interface by N 2 O plasma oxidation

The conduction in GaN Schottky junctions with HfO 2 passivation layers can be improved by post-deposition annealing (PDA). Surface defects and ionic states of Ga-polar GaN removed by PDA lead to the formation of downward bend banding with a positive surface polarity. X-ray photoelectron spectroscopy is utilized to assess the effects of PDA on the atomic composition and surface polarity changes at the HfO 2 /GaN interface and GaN surface. The leakage current level and ideality factor of the GaN Schottky junctions improved from 4.73 × 10 −6 A cm −2 to 8.21 × 10 −8 A cm −2 and from 1.47 to 1.14, respectively. With the application of PDA, the flow of leakage current through the Schottky metal area reduced as the surface defect states were removed.

Improved conduction in GaN Schottky junctions with HfO₂ passivation layers through post-deposition annealing

Kim¹

2020

Analysis of simultaneous occurrence of shallow surface Fermi level pinning and deep depletion in MOS diode with Mg-ion-implanted GaN before activation annealing

Akazawa

Kamoshida

2020

Self Cite

The characteristics of a MOS diode with Mg-ion-implanted GaN before activation annealing were investigated. Mg ion implantation onto n-GaN with slightly high Si doping concentration (5×10 17 cm -3 ) was performed with a moderate dosage (1.5×10 12 cm -2 ). The completed MOS diode showed n-type features. The capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of the MOS diode indicated that shallow surface Fermi level pinning and deep depletion occurred simultaneously. By applying the conductance method to the measured C-f characteristics, a discrete level at 0.2-0.3 eV below the conduction band edge was detected. On the basis of the simulation of the high-frequency-limit C-V curve, the detected discrete level distributed in the bulk of n-GaN rather than at the insulator/semiconductor interface, so that it caused surface Fermi level pinning at a relatively shallow energy level and deep depletion owing to its acceptorlike nature simultaneously.

Low-temperature annealing behavior of defects in Mg-ion-implanted GaN studied using MOS diodes and monoenergetic positron beam

Akazawa

Kamoshida

Murai

et al. 2020

Self Cite

Mg ions were implanted into Si-doped (5 × 1017 cm–3) n-GaN at a dose of 1.5 × 1011 or 1.5 × 1012 cm–2. MOS diodes were used to characterize the implanted GaN after 300 °C annealing for 3 h and after additional 500 °C annealing for 3 min. Although capacitance–voltage (C–V) characteristics varied with the dosage, the effects of acceptor-like defects induced by ion implantation were observed in the C–V characteristics independently of dosage and annealing temperature. A defect level at approximately 0.25 eV below the conduction band edge was detected electrically. By positron annihilation spectroscopy, its origin was identified as a divacancy consisting of Ga and N vacancies. It was found that its density compared with that of as-implanted GaN decreased with 300 °C annealing, and further increased with 500 °C annealing. This phenomenon was explained on the basis of the difference between the diffusion barriers of possible point defects.