H-Atom Incorporation in Mg-Doped GaN Grown by Metalorganic Chemical Vapor Deposition

Ohba, Yasuo; Hatano, Ako

doi:10.1143/jjap.33.l1367

Cited by 46 publications

(14 citation statements)

References 9 publications

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“…This has been for instance shown by the occurrence of LO mode in IR absorption, and recently by the observation of the Mg-H local vibration modes (LVM) [4] [14]. Measurements of depth profiles showed that Mg and H are incorporated simultaneously [15]. This H passivation limits the electrical activity of Mg, therefore an activation process is required to get full electrical activity of the Mg atoms.…”

Section: Introductionmentioning

confidence: 99%

p-doping of GaN by MOVPE

Haffouz

Beaumont

Leroux

et al. 1997

MRS Internet j. nitride semicond. res.

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Mg has been widely used as p-doping species despite its intrinsic difficulties. It is nowadays well established that during the growth process of Mg doped GaN, atomic H is generated from the decomposition of NH 3 and Mg-H complexes are formed in the layer. This has been for instance shown by the occurrence of LO mode in IR absorption, and by the observation of the Mg-H local vibration modes. This H passivation limits the electrical activity of Mg, therefore an activation process is required to get full activation of the Mg atoms. In the present study, bismethylcyclopentadienyl magnesium [(MeCp) 2 Mg] was used as precursor. However, this precursor reacts in the gas phase with NH 3 to produce tiny solid particles as evidenced by a very bright diffuse emission visible along the laser beam used for reflectometry measurements. This simplest obvious product would be [(MeCp)Mg(NH 2 )] m (m≥2). To limit this drawback, Ga and Mg precursor lines have been separated. With proper in situ heat treatment, doping densities up to 1.5x10 18 cm -3 have been obtained. PL spectra of lightly Mg doped samples (10 16 cm -3 ) are dominated by shallow donor-acceptor pairs whereas for higher doping densities ( 10 18 cm -3 ), the luminescence is dominated by a broad band in the 2.7-2.9 eV range. GaN LEDs were fabricated from Si doped (n-type) and Mg-doped (p-type) GaN, these LEDs emit in the blue-UV range.

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Section: Introductionmentioning

confidence: 99%

p-doping of GaN by MOVPE

Haffouz

Beaumont

Leroux

et al. 1997

MRS Internet j. nitride semicond. res.

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“…12 In previous studies, the amount of hydrogen was found to increase linearly with the Mg concentration in the as-grown MOVPE GaN:Mg samples. 13 After annealing, the hydrogen density would decrease in general, but the exact relationship between the amount of hydrogen extraction, the Mg doping level, and the annealing time is not presently clear.…”

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confidence: 99%

Electrical characterization of Mg-doped GaN grown by metalorganic vapor phase epitaxy

Huang

Kuech

et al. 1996

Applied Physics Letters

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We have applied frequency-dependent capacitance measurements and admittance spectroscopy on GaN:Mg to study the electronic states associated with Mg doping. Metalorganic vapor phase epitaxy GaN:Mg samples with two different Mg doping levels were grown and thermally annealed in nitrogen. Lateral dot-and-ring Schottky diodes using Au/Ti were fabricated. Frequency-dependent measurements on these diodes show that the capacitance is reduced at a higher frequency, most likely due to the inability of a deep center to maintain an equilibrium ionization state under a high-frequency modulation. Admittance spectroscopy, in which the conductance is monitored as a function of temperature, verifies the existence of one impurity-related acceptor level in the higher Mg-doped sample with an activation energy of 136 meV. For the lower Mg-doped sample, two acceptor levels at 124 and 160 meV were observed. We believe these levels are most probably associated with the Mg acceptor state itself, possessing energy levels which are very close to the results previously reported in the literature. © 1996 American Institute of Physics. ͓S0003-6951͑96͒01617-9͔The successful p-type doping in metalorganic vapor phase epitaxy ͑MOVPE͒ GaN using Mg has allowed the realization of blue light emitting p-n junction diodes. Treatments, such as electron-beam irradiation 1 or thermal annealing, 2 are usually required to activate the p-type conduction. Electrical characteristics of these Mg-related acceptors are, however, not well understood. The Mg acceptor binding energy has been reported to be 250 and ϳ160 meV from the donor-acceptor pair transition and from temperature-dependent photoluminescence ͑PL͒ experiments, respectively.3 The temperature-dependent Hall measurements revealed a Mg-related activation energy of 157 meV. 4 In this letter, we report the electrical characterization of GaN:Mg, using frequency-dependent capacitance measurements and admittance spectroscopy, in order to study the electronic states associated with Mg doping. It is well known that deep traps greatly affect the free carrier profiles, as determined by capacitance-voltage (C -V) measurements. 5Given the aforementioned energy level depths associated with Mg, as well as the fact that Mg-doping is responsible for most or all of the observed p-type conductivity, the small signal capacitance of Mg-doped GaN is expected to be dependent on measurement frequency. We had also found that deep level transient spectroscopy ͑DLTS͒ could not be successfully used to characterize these Mg-related deep levels, principally due to the low diode capacitance level at low measurement temperatures. In contrast, admittance spectroscopy is better suited for the study of these relatively shallow and/or fast levels. Mg-doped GaN samples were grown in a horizontal MOVPE reactor at 100 Torr using trimethyl gallium ͑TMGa͒, bis-cyclopentadienyl magnesium ͑Cp 2 Mg), and ammonia (NH 3 ) on ͑0001͒ sapphire substrates.7 The Mgdoped layer, ϳ2 m in thickness, was grown at 1050°C at a growth rate of ϳ2 m/h. Two ...

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“…In order to improve the performances of the LEDs, highly conductive p-type GaN and reliable ohmic contacts are required. However, the as-grown p-type GaN is of high resistance due to the Mg-H complexes [4][5][6]. In order to dissociate the Mg-H complexes, thermal annealing at above 700°C in N 2 ambient is usually employed [7,8].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of GaN-based light-emitting diodes without pre-activation of p-type GaN

Hu¹,

Wang²,

Zhang³

2016

Nano Online

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We fabricated GaN-based light-emitting diodes (LEDs) without pre-activation of p-type GaN. During the fabrication process, a 100-nm-thick indium tin oxide film was served as the p-type contact layer and annealed at 500°C in N 2 ambient for 20 min to increase its transparency as well as to activate the p-type GaN. The electrical measurements showed that the LEDs were featured by a lower forward voltage and higher wall-plug efficiency in comparison with LEDs using pre-activation of p-type GaN. We discussed the mechanism of activation of p-type GaN at 500°C in N 2 ambient. Furthermore, x-ray photoemission spectroscopy examinations were carried out to study the improved electrical performances of the LEDs without pre-activation of p-type GaN.

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H-Atom Incorporation in Mg-Doped GaN Grown by Metalorganic Chemical Vapor Deposition

Cited by 46 publications

References 9 publications

p-doping of GaN by MOVPE

p-doping of GaN by MOVPE

Electrical characterization of Mg-doped GaN grown by metalorganic vapor phase epitaxy

Fabrication and characterization of GaN-based light-emitting diodes without pre-activation of p-type GaN

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