Oxygen diffusion into SiO2-capped GaN during annealing

Pearton, S. J.; Cho, H.; LaRoche, J. R.; Ren, F.; Wilson, R. G.; Lee, J. W.

doi:10.1063/1.125194

Cited by 75 publications

(46 citation statements)

References 19 publications

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“…1, 2). Diffusion coefficient of oxygen calculated from the oxygen profile in epitaxial GaN amounts ~3×10 -13 cm 2 /s and is in good agreement with data reported in [7]. Diffusion rate was lower than MOCVD growth rate.…”

Section: Resultssupporting

confidence: 88%

Oxygen diffusion into GaN from oxygen implanted GaN or Al₂O₃

Jakieła

Dumiszewska

Caban

et al. 2011

Phys. Status Solidi C

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Thermal diffusion and incorporation of oxygen in gallium nitride during MOVPE growth process was investigated using secondary ion mass spectroscopy. The source of oxygen were (18O) implanted into GaN or Al2O3 substrate. Experiment shows no oxygen diffusion from Ar‐implanted sapphire or O‐implanted GaN and extremely deep diffusion from O‐implanted sapphire. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultssupporting

confidence: 88%

Oxygen diffusion into GaN from oxygen implanted GaN or Al₂O₃

Jakieła

Dumiszewska

Caban

et al. 2011

Phys. Status Solidi C

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“…24 On the other hand, the diffusion of oxygen atoms by annealing at 500-900°C has been reported for SiO 2 / GaN interfaces. 25 Thus, it is highly likely that oxygen had a decaying distribution in the AlGaN layer before the surface control process and that this distribution was changed during the surface control process at 700°C. The result indicates that the present surface control process efficiently removes oxygen donors having a decaying distribution from the surface and realizes the intrinsic constant donor density of Si.…”

Section: C-v Characterization Of Surface Control Processmentioning

confidence: 99%

Large reduction of leakage currents in AlGaN Schottky diodes by a surface control process and its mechanism

Kotani

Kaneko

Hasegawa

et al. 2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Leakage currents in AlGaN Schottky diodes were investigated systematically by using a rigorous computer simulation based on the thin surface barrier model taking account of unintentionally doped surface donors. The leakage currents in AlGaN Schottky diodes have stronger bias dependence and smaller temperature dependences as compared with those of GaN diodes. It was shown that these features were associated with shallow oxygen donors located near the AlGaN surface. Then, an attempt was made to remove oxygen and suppress leakage currents by a surface control process using an ultrathin Al layer and subsequent annealing. An in situ x-ray photoelectron spectroscopy analysis indicated the formation of Al 2 O 3 layer during the surface control process, suggesting efficient gettering of oxygen from the surface. C-V analysis directly indicated the reduction of shallow donors by the surface control process. A remarkable reduction of reverse leakage currents of four to five orders of magnitude took place in large area AlGaN Schottky diodes after the application of the surface control process. This process also reduced leakage currents of the gate of the heterostructure field effect transistor device by more than one order of magnitude and increased temperature dependences of current.

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“…However, as there exist only a few experimental studies of oxygen in GaN, the fundamental origin and role of the oxygen in determining the overall electronic characteristics of the films is poorly understood. For example, it has been suggested that oxygen in GaN may originate as an impurity in the NH 3 precursor for metal organic chemical vapor deposition (MOCVD), or may originate from the remnant water vapor in molecular beam epitaxy (MBE) [5]. Another suggestion is that oxygen from the Al 2 O 3 substrate may diffuse within the disordered interfacial region, creating donors responsible for the formation of an impurity band [6].…”

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confidence: 99%

Role of Oxygen at Screw Dislocations in GaN

2003

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Here we report the first direct atomic scale experimental observations of oxygen segregation to screw dislocations in GaN using correlated techniques in the scanning transmission electron microscope. The amount of oxygen present in each of the three distinct types of screw dislocation core is found to depend on the evolution and structure of the core, and thus gives rise to a varying concentration of localized states in the band-gap. Contrary to previous theoretical predictions, the substitution of oxygen for nitrogen is observed to extend over many monolayers for the open core dislocation. 1In recent years, GaN has developed into an important semiconductor for optical and electronic applications. However, due to a large lattice mismatch with the substrate, the material possesses an overall high density of threading dislocations. While efforts have been made to reduce dislocation density, the remaining dislocations still play an important role in device performance, one that is still not well understood. The previous work of Nakamura and others in fabricating GaN-based blue and green light emitting diodes (LED's) and commercializing nitride laser diodes [1,2] has proven functionality for GaN devices irrespective of impurities and dislocations, but an explanation of changes in device performance and efficiency over time is still pending. In fact, most purely intrinsic dislocations appear not to be related to device failure [3,4]. It therefore appears that the interaction of dislocations with impurities, and in particular, oxygen, may create impurity states in the band gap, act as traps for carriers, and could prove to be one of the key sources of device breakdown.Oxygen is an impurity that is known to be present in GaN thin films. However, as there exist only a few experimental studies of oxygen in GaN, the fundamental origin and role of the oxygen in determining the overall electronic characteristics of the films is poorly understood. For example, it has been suggested that oxygen in GaN may originate as an impurity in the NH 3 precursor for metal organic chemical vapor deposition A further complication to understanding the complex role of oxygen is how it interacts with the abundant dislocation cores in GaN, and whether the combination of impurity plus dislocation produces either a deleterious or benign effect. In this letter,we address the issue of impurity segregation to one of the three types of dislocations in GaN, the screw dislocation. More specifically, we provide direct experimental observations on the segregation of oxygen to three variants of screw dislocations: open core, filled core, and full core, and its effect on the electronic structure. These measurements provide evidence in favor of the interaction of oxygen with screw dislocations providing the origin of localized states at the cores.The experimental techniques used in this analysis are Z-contrast imaging and electron energy loss spectroscopy (EELS) performed in a JEOL 2010F 200kV scanning transmission electron microscope (STEM) [10]. In a Z-...

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Oxygen diffusion into SiO2-capped GaN during annealing

Cited by 75 publications

References 19 publications

Oxygen diffusion into GaN from oxygen implanted GaN or Al₂O₃

Oxygen diffusion into GaN from oxygen implanted GaN or Al₂O₃

Large reduction of leakage currents in AlGaN Schottky diodes by a surface control process and its mechanism

Role of Oxygen at Screw Dislocations in GaN

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Oxygen diffusion into SiO2-capped GaN during annealing

Cited by 75 publications

References 19 publications

Oxygen diffusion into GaN from oxygen implanted GaN or Al2O3

Oxygen diffusion into GaN from oxygen implanted GaN or Al2O3

Large reduction of leakage currents in AlGaN Schottky diodes by a surface control process and its mechanism

Role of Oxygen at Screw Dislocations in GaN

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Oxygen diffusion into GaN from oxygen implanted GaN or Al₂O₃

Oxygen diffusion into GaN from oxygen implanted GaN or Al₂O₃