Variable Energy Positron Annihilation Spectroscopy of GaN Grown on Sapphire Substrates with MOCVD

Hu, Yifan; Beling, C. D.; Fung, S.

doi:10.1088/0256-307x/22/5/053

Cited by 3 publications

(2 citation statements)

References 12 publications

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“…This suggests that larger voids grow after annealing above 500°C. Similar voids were also observed by Fan et al 43 in GaN films implanted with Al + immediately after implantation.…”

Section: Resultssupporting

confidence: 87%

“…For example, S N for monovacancies is 1.030, S N for divacancies is 1.034-1.044, small vacancy clusters are expected to have 1.05-1.07, and for voids S N is 1.10-1.14. 43,44 From Fig. 3, it can be seen that for the unimplanted sample, the S N parameter decreases gradually from the surface state to the bulk state with increasing energy, and becomes constant at E Ͼ 10 keV.…”

Section: Resultsmentioning

confidence: 96%

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Experimental elucidation of vacancy complexes associated with hydrogen ion-induced splitting of bulk GaN

et al. 2010

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We present a detailed study of the thermal evolution of H ion-induced vacancy related complexes and voids in bulk GaN implanted under ion-cut conditions. By using transmission electron microscopy, we found that the damage band in as-implanted GaN is decorated with a high density of nanobubbles of ϳ1 -2 nm in diameter. Variable energy Doppler broadening spectroscopy showed that this band contains vacancy clusters and voids. In addition to vacancy clusters, the presence of V Ga , V Ga -H 2 , and V Ga V N complexes was evidenced by pulsed low-energy positron lifetime spectroscopy. Subtle changes upon annealing in these vacancy complexes were also investigated. As a general trend, a growth in open-volume defects is detected in parallel to an increase in both size and density of nanobubbles. The observed vacancy complexes appear to be stable during annealing. However, for temperatures above 450°C, unusually large lifetimes were measured. These lifetimes are attributed to the formation of positronium in GaN. Since the formation of positronium is not possible in a dense semiconductor, our finding demonstrates the presence of sufficiently large open-volume defects in this temperature range. Based on the Tao-Eldrup model, the average lattice opening during thermal annealing was quantified. We found that a void diameter of 0.4 nm is induced by annealing at 600°C. The role of these complexes in the subsurface microcracking is discussed.

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“…This suggests that larger voids grow after annealing above 500°C. Similar voids were also observed by Fan et al 43 in GaN films implanted with Al + immediately after implantation.…”

Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 96%

Experimental elucidation of vacancy complexes associated with hydrogen ion-induced splitting of bulk GaN

et al. 2010

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Surface Erosion of GaN Bombarded by Highly Charged ²⁰⁸ Pb ^{q
+} -Ions

Zhang

Yang

et al. 2008

Chinese Phys. Lett.

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Surface change of gallium nitride specimens after bombardment by highly charged Pbq+-ions (q = 25, 35) at room temperature is studied by means of atomic force microscopy. The experimental results reveal that the surface of GaN specimens is significantly etched and erased. An unambiguous step-up is observed. The erosion depth not only strongly depends on the charge state of ions, but also is related to the incident angle of Pbq+-ions and the ion dose. The erosion depth of the specimens in 60° incidence (tilted incidence) is significantly deeper than that of the normal incidence. The erosion behaviour of specimens has little dependence on the kinetic energy of ion (Ek = 360,700keV). On the other hand, surface roughness of the irradiated area is obviously decreased due to erosion compared with the un-irradiated area. A flat terrace is formed.

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Cu diffusion-induced vacancy-like defects in freestanding GaN

et al. 2011

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Variable Energy Positron Annihilation Spectroscopy of GaN Grown on Sapphire Substrates with MOCVD

Cited by 3 publications

References 12 publications

Experimental elucidation of vacancy complexes associated with hydrogen ion-induced splitting of bulk GaN

Experimental elucidation of vacancy complexes associated with hydrogen ion-induced splitting of bulk GaN

Surface Erosion of GaN Bombarded by Highly Charged ²⁰⁸ Pb ^{q
+} -Ions

Cu diffusion-induced vacancy-like defects in freestanding GaN

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Variable Energy Positron Annihilation Spectroscopy of GaN Grown on Sapphire Substrates with MOCVD

Cited by 3 publications

References 12 publications

Experimental elucidation of vacancy complexes associated with hydrogen ion-induced splitting of bulk GaN

Experimental elucidation of vacancy complexes associated with hydrogen ion-induced splitting of bulk GaN

Surface Erosion of GaN Bombarded by Highly Charged 208 Pb q + -Ions

Cu diffusion-induced vacancy-like defects in freestanding GaN

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Surface Erosion of GaN Bombarded by Highly Charged ²⁰⁸ Pb ^{q
+} -Ions