Photoluminescence of Mg-doped p-type GaN and electroluminescence of GaN p-n junction LED

Akasaki, Isamu; Amano, Hiroshi; Kito, M.; Hiramatsu, Kazumasa

doi:10.1016/0022-2313(91)90215-h

Cited by 275 publications

(124 citation statements)

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“…The maximum sustained concentration of Mg obtained in GaN films using the MME technique was above 7 ϫ 10 20 cm −3 , leading to a hole concentration as high as 4.5ϫ 10 18 cm −3 at room temperature, with a mobility of 1. GaN,7 unintentional hydrogen and oxygen doping, 8,9 a significant compensation of Mg acceptors at high dopant concentrations, 1 and a drastic dependence of incorporation upon the growth regime or III-V ratio.10,11 As a consequence, there is a narrow window of growth conditions, which yield electrically active p-type GaN. Furthermore, even low or moderate hole concentrations are often not consistently obtained and are difficult to reproduce due to the Mg incorporation sensitivity to growth conditions.…”

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confidence: 99%

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Reproducible increased Mg incorporation and large hole concentration in GaN using metal modulated epitaxy

Burnham¹,

Namkoong²,

Look³

et al. 2008

Journal of Applied Physics

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The metal modulated epitaxy ͑MME͒ growth technique is reported as a reliable approach to obtain reproducible large hole concentrations in Mg-doped GaN grown by plasma-assisted molecular-beam epitaxy on c-plane sapphire substrates. An extremely Ga-rich flux was used, and modulated with the Mg source according to the MME growth technique. The shutter modulation approach of the MME technique allows optimal Mg surface coverage to build between MME cycles and Mg to incorporate at efficient levels in GaN films. The maximum sustained concentration of Mg obtained in GaN films using the MME technique was above 7 ϫ 10 20 cm −3 , leading to a hole concentration as high as 4.5ϫ 10 18 cm −3 at room temperature, with a mobility of 1. GaN,7 unintentional hydrogen and oxygen doping, 8,9 a significant compensation of Mg acceptors at high dopant concentrations, 1 and a drastic dependence of incorporation upon the growth regime or III-V ratio.10,11 As a consequence, there is a narrow window of growth conditions, which yield electrically active p-type GaN. Furthermore, even low or moderate hole concentrations are often not consistently obtained and are difficult to reproduce due to the Mg incorporation sensitivity to growth conditions. These complications result in large and varied resistances and mobilities in GaN-based devices that rely on p-type layers. If hole carrier concentrations were to be increased, and p-type doping of GaN standardized, these devices could benefit from better performance and better reliability.Despite the complications associated with Mg-doped GaN, current state-of-the-art reports show promising results and give a reference for comparison. Mg incorporation as determined by secondary ion mass spectroscopy ͑SIMS͒ has been reported to be as high as 8 ϫ 10 20 cm −3 for metal organic chemical vapor deposition 12 and 3.5ϫ 10 20 cm −3 for molecular beam epitaxy ͑MBE͒.13 However, above approximately ͑2 -3.5͒ ϫ 10 20 cm −3 , the Mg incorporation begins to decrease with increased Mg flux 13 and inverts Ga-polar films to N-polar. 14 M-plane ͑1010͒ oriented substrates have been used to achieve a hole concentration as high as p = 7.2 ϫ 10 18 cm −3 .15 Electrical characterization for current stateof-the-art films grown on c-plane substrates is shown in Table I. [16][17][18] Reasonably high hole carrier concentrations are in the range of ͑1-3͒ ϫ 10 18 cm −3 . However, hole concentrations have been reported to be as high as 6 ϫ 10 18 cm −3 , 18 although the carrier concentration was metastable and significantly reduced upon heating during measurement. The metal modulated epitaxy ͑MME͒ growth technique was developed to specifically address reproducibility issues. [19][20][21][22] The MME growth technique is characterized by a group-III ͑metal͒ flux much higher than the group-V source, which would normally lead to droplets. However, the metal shutter is modulated to avoid droplet buildup and therefore build and deplete the metal bilayer on the growth surface, yielding smoother surfaces, larger grain sizes, and better repr...

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confidence: 99%

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Reproducible increased Mg incorporation and large hole concentration in GaN using metal modulated epitaxy

Burnham¹,

Namkoong²,

Look³

et al. 2008

Journal of Applied Physics

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“…1,2 The further realization that activation of hydrogenpassivated Mg acceptors by thermal annealing could produce p-type GaN opened the door for many device demonstrations including light-emitting diodes, laser, detectors, and transistors. [3][4][5][6][7][8][9][10] While further advances in material quality will lead to additional device improvements, many advanced device structures will require improvements in device processing technology as well. One area of processing technology that should play an enabling role, particularly for electronic devices, is ion implantation, which can be used to produce selective area doping or compensation.…”

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Electrical and structural analysis of high-dose Si implantation in GaN

Zolper

Tan

Williams

et al. 1997

Applied Physics Letters

110

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For the development of ion implantation processes for GaN to advanced devices, it is important to understand the dose dependence of impurity activation along with implantation-induced damage generation and removal. We find that Si implantation in GaN can achieve 50% activation at a dose of 1×1016 cm−2, despite significant residual damage after the 1100 °C activation anneal. The possibility that the generated free carriers are due to implantation damage alone and not Si-donor activation is ruled out by comparing the Si results to those for implantation of the neutral species Ar. Ion channeling and cross-sectional transmission electron microscopy are used to characterize the implantation-induced damage both as implanted and after a 1100 °C anneal. Both techniques confirm that significant damage remains after the anneal, which suggests that activation of implanted Si donors in GaN doses not require complete damage removal. However, an improved annealing process may be needed to further optimize the transport properties of implanted regions in GaN.

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“…However, there is a limited number of possible candidates both for the shallow acceptor and the shallow donor(s) involved in the DAP. For the shallow acceptor with an optical binding energy of around 225 meV, Mg Ga [8,9] is the most promising candidate. Whereas possible candidates for the shallow donor (20-30 meV) are O [10], Si [11], H [12] and V N -H [13].…”

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confidence: 99%

Formation and dissociation of hydrogen-related defect centers in Mg-doped GaN

et al. 2003

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Moderately and heavily Mg-doped GaN were studied by a combination of post-growth annealing processes and electron beam irradiation techniques during cathodoluminescence (CL) to elucidate the chemical origin of the recombination centers responsible for the main optical emission lines. The shallow donor at 20-30 meV below the conduction band, which is involved in the donor-acceptor-pair (DAP) emission at 3.27 eV, was attributed to a hydrogen-related center, presumably a (V N -H) complex. Due to the small dissociation energy (<2 eV) of the (V N -H) complex, this emission line was strongly reduced by low-energy electron irradiation. CL investigations of the DAP at a similar energetic position in Si-doped (n-type) GaN indicated that this emission line is of different chemical origin than the 3.27 eV DAP in Mg-doped GaN. A slightly deeper DAP emission centered at 3.14 eV was observed following low-energy electron irradiation, indicating the appearance of an additional donor level with a binding energy of 100-200 meV, which was tentatively attributed to a V N -related center. The blue band (2.8-3.0 eV) in heavily Mg-doped GaN was found to consist of at least two different deep donor levels at 350±30 meV and 440±40 meV. The donor level at 350±30 meV was strongly affected by electron irradiation and attributed to a H-related defect.

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Photoluminescence of Mg-doped p-type GaN and electroluminescence of GaN p-n junction LED

Cited by 275 publications

References 2 publications

Reproducible increased Mg incorporation and large hole concentration in GaN using metal modulated epitaxy

Reproducible increased Mg incorporation and large hole concentration in GaN using metal modulated epitaxy

Electrical and structural analysis of high-dose Si implantation in GaN

Formation and dissociation of hydrogen-related defect centers in Mg-doped GaN

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