Studies on atomic layer deposition Al2O3/In0.53Ga0.47As interface formation mechanism based on air-gap capacitance-voltage method Appl. Phys. Lett. 101, 122102 (2012) A mathematical model for void evolution in silicon by helium implantation and subsequent annealing process J. Appl. Phys. 112, 064302 (2012) Void evolution in silicon under inert and dry oxidizing ambient annealing and the role of a Si1−xGex epilayer cap Defects in hydrothermal grown ZnO single crystals are studied as a function of annealing temperature using positron annihilation, x-ray diffraction, Rutherford backscattering, Hall, and cathodoluminescence measurements. Positron lifetime measurements reveal the existence of Zn vacancy related defects in the as-grown state. The positron lifetime decreases upon annealing above 600°C, which implies the disappearance of Zn vacancy related defects, and then remains constant up to 900°C. The Rutherford backscattering and x-ray rocking curve measurements show the improvement of crystal quality due to annealing above 600°C. Although the crystal quality monitored by x-ray diffraction measurements is further improved after annealing at above 1000°C, the positron lifetime starts to increase. This is due to either the formation of Zn vacancy related defects, or the change of the Zn vacancy charge state occupancy as a result of the Fermi level movement. The electron concentration increases continuously with increasing annealing temperature up to 1200°C, indicating the formation of excess donors, such as oxygen vacancies or zinc interstitials. The cathodoluminescence measurements reveal that the ultraviolet emission is greatly enhanced in the same temperature range. The experimental results show that the ZnO crystal quality, electrical and optical characteristics are improved by postgrowth annealing from 600 to 1200°C. The disappearance of Zn vacancy related defects contributes to the initial stage of improved crystal quality.
Irradiation of fast particles like 1 MeV electrons and 2 MeV protons was made for single crystalline cubic silicon carbide (3C‐SiC) grown epitaxially on Si by chemical vapor deposition in order to introduce point defects in the material. Intrinsic point defects in 3C‐SiC have been characterized by electron spin resonance (ESR), positron annihilation spectroscopy (PAS), Hall and photoluminescence (PL) techniques. The structure and annealing behavior of intrinsic defects, e.g. monovacancies at silicon and carbon sublattice sites, are described based on the results obtained by ESR and PAS. The contributions of such point defects to electrical and optical properties of 3C‐SiC are discussed using the Hall and PL results, with a brief review of published work.
Articles you may be interested inReuse of AIP Publishing content is subject to the terms at: https://publishing.aip.org/authors/rights-and-permissions. Phosphorus ions were implanted in ZnO single crystals with energies of 50-380 keV having total doses of 4.2ϫ 10 13 -4.2ϫ 10 15 cm −2 . Positron annihilation measurements reveal the introduction of vacancy clusters after implantation. These vacancy clusters grow to a larger size after annealing at a temperature of 600°C. Upon further annealing up to a temperature of 1100°C, the vacancy clusters gradually disappear. Raman-scattering measurements reveal the enhancement of the phonon mode at approximately 575 cm −1 after P + implantation, which is induced by the production of oxygen vacancies ͑V O ͒. These oxygen vacancies are annealed out up to a temperature of 700°C accompanying the agglomeration of vacancy clusters. The light emissions of ZnO are suppressed after implantation. This is due to the competing nonradiative recombination centers introduced by implantation. The recovery of the light emission occurs at temperatures above 600°C. The vacancy-type defects detected by positrons might be part of the nonradiative recombination centers. The Hall measurement indicates an n-type conductivity for the P + -implanted ZnO layer, suggesting that phosphorus is an amphoteric dopant.
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