Compensation mechanism in MOCVD and MBE grown GaN:Mg

Alves, H.; Böhm, Matthias; Hofstaetter, A.; Amano, Hiroshi; Einfeldt, S.; Hommel, D.; Hofmann, Detlev M.; Meyer, B. K.

doi:10.1016/s0921-4526(01)00663-9

Cited by 28 publications

(15 citation statements)

References 9 publications

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“…Previous studies of Mg incorporation in GaN have shown a plateau in free hole concentration with increased Mg incorporation, 4 suggesting the formation of holepassivating defects at high Mg concentrations, although this critical fraction of Mg is likely dependent on growth parameters. Nearly all studies of the electronic properties of p-type GaN have been conducted on large-scale device structures, and are therefore largely insensitive to microscale and nanoscale variations in electrical behavior that may exist.…”

Section: Introductionmentioning

confidence: 97%

Local conductivity and surface photovoltage variations due to magnesium segregation in p-type GaN

Simpkins

Chowdhury

et al. 2004

Journal of Applied Physics

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Conductive atomic force microscopy ͑C-AFM͒ and surface photovoltage ͑SPV͒ microscopy were used to investigate local electronic structure in p-type GaN. C-AFM imaging revealed locally reduced forward-and reverse-bias conductivity near threading dislocations. In addition, regions near threading dislocations demonstrated significantly enhanced surface photovoltage response when compared to regions away from dislocations. Analytical treatment of the surface photovoltage as a function of pertinent material properties indicated that reduced background dopant concentration is the most likely cause for the increased SPV. Both reduced conductivity and enhanced surface photovoltage are shown to be consistent with Mg segregation to dislocation cores that results in regions of locally decreased electrically active Mg concentration surrounding the dislocations.

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Section: Introductionmentioning

confidence: 97%

Local conductivity and surface photovoltage variations due to magnesium segregation in p-type GaN

Simpkins

Chowdhury

et al. 2004

Journal of Applied Physics

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“…2 Finally, MOCVD growth of Mg-doped GaN is seen to lead to saturation in hole concentration, potentially related to formation of Mg precipitates. 3,4 The formation of Mg precipitates has not been observed in MBE grown GaN.…”

Section: Introductionmentioning

confidence: 99%

Polarity control during molecular beam epitaxy growth of Mg-doped GaN

Green

Haus

et al. 2003

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

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Mg doping has been found in some situations to invert growth on Ga-face GaN to N-face. In this study, we clarified the role the Ga wetting layer plays in rf plasma molecular beam epitaxy of GaN when Mg doping, for [Mg] from ∼2×1019 to ∼1×1020 cm−3 corresponding to the useful, accessible range of hole concentrations of p∼1017–1018 cm−3. Structures were grown in the N-rich and Ga-rich growth regime for single Mg doping layers and for multilayer structures with a range of Mg concentrations. Samples were characterized in situ by reflection high-energy electron diffraction and ex situ by atomic force microscopy, transmission electron microscopy, convergent beam electron diffraction, and secondary ion mass spectroscopy. Growth on “dry” surfaces (without a Ga wetting layer) in the N-rich regime completely inverted to N-face upon exposure to Mg. No reinversion to Ga-face was detected for subsequent layers. Additionally, Mg was seen to serve as a surfactant during this N-rich growth, as has been reported by others. Growth initiated in the Ga-rich regime contained inversion domains that nucleated with the initiation of Mg doping. No new inversion domains were found as the Mg concentration was increased through the useful doping levels. Thus the Ga wetting layer was found to inhibit nucleation of N-face GaN, though a complete wetting layer took time to develop. Finally, by establishing a complete Ga wetting layer on the surface prior to growth, we confirmed this finding and demonstrated Mg-doped GaN completely free from inversion domains to a doping level of [Mg]∼2×1020.

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“…The discovery of the p-type doping of nitride semiconductors using Magnesium (Mg) impurities in 1989 [1][2][3] enabled novel optoelectronic applications, the main one being the developement of energy saving solid state lighting [4]. However, reaching high hole concentration in nitrides is challenging due to the limited solubility of Mg in GaN, to the high activation energy of the Mg acceptor and to compensation problems [5][6][7]. The nanowire (NW) geometry is favorable for nitride p-doping thanks to a decreased formation energy of defects at the surface [8] and to the possibility to relax the compressive strain induced by Mg incorporation [9,10].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the effect of the doping order in GaN nanowire p–n junctions grown by molecular-beam epitaxy

et al. 2020

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We analyse the electrical and optical propreties of single GaN nanowire p-n junctions grown by plasma-assisted molecular-beam epitaxy using magnesium and silicon as doping sources. Different junction architectures having either a n-base or a p-base structure are compared using optical and electrical analyses. Electron-beam induced current microscopy of the nanowires shows that in the case of a n-base p-n junction the parasitic radial growth enhanced by the Mg doping leads to a mixed axial-radial behavior with strong wire-to-wire fluctuations of the junction position and shape. By reverting the doping order p-base p-n junctions with a purely axial well-defined structure and a low wire-to-wire dispersion are achieved. The good optical quality of the top n nanowire segment grown on a p-doped stem is preserved. A hole concentration in the p-doped segment exceeding 10 18 cm -3 was extracted from electron beam induced current mapping and photoluminescence analyses. This high concentration is reached without degrading the nanowire morphology.

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Compensation mechanism in MOCVD and MBE grown GaN:Mg

Cited by 28 publications

References 9 publications

Local conductivity and surface photovoltage variations due to magnesium segregation in p-type GaN

Local conductivity and surface photovoltage variations due to magnesium segregation in p-type GaN

Polarity control during molecular beam epitaxy growth of Mg-doped GaN

Investigation of the effect of the doping order in GaN nanowire p–n junctions grown by molecular-beam epitaxy

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