Local vibrational modes in Mg-doped gallium nitride

Brandt, Martin S.; Ager, Joel W.; Götz, Werner; Johnson, N. M.; Harris, Joshua S.; Molnar, R. J.; Moustakas, T. D.

doi:10.1103/physrevb.49.14758

Cited by 70 publications

(39 citation statements)

References 10 publications

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“…Only about 1% of the magnesium acceptors are ionised at room temperature. Two LVMs in the 2000 cm ± ±1 range had been attributed to two non-equivalent configurations of the Mg±H complex in GaN [24], but, to our knowledge, this result has never been reproduced and should be considered as doubtful.…”

contrasting

confidence: 49%

Acceptor Neutralisation by Hydrogen in GaN and Wide Band Gap II-VI Materials

Clerjaud¹,

Côté

Lebkiri

1998

phys. stat. sol. (b)

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contrasting

confidence: 49%

Acceptor Neutralisation by Hydrogen in GaN and Wide Band Gap II-VI Materials

Clerjaud¹,

Côté

Lebkiri

1998

phys. stat. sol. (b)

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“…14 A recent Raman and infrared absorption spectroscopic study by Brandt et al 15 has demonstrated the existence of four local vibrational modes for samples of GaN:Mg possessing a high concentration of hydrogen. One pair of the modes, with room-temperature frequencies of 2168 and 2219 cm Ϫ1 , is assigned to Mg-H complexes in the c plane and parallel to the c axis.…”

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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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“…It has also been speculated that hydrogen forms complexes with impurities in GaN and could modify its electronic behavior. Hydrogen atoms neutralize Mg acceptors in GaN [15][16][17] and complexes of multiple hydrogens with native defects, in particular vacancies, have also been investigated 18,19 . Furthermore, complexes of hydrogen with carbon, have also been also studied in relation to the blue luminescence 20 .…”

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confidence: 99%

A first-principles study of carbon-related energy levels in GaN. II. Complexes formed by carbon and hydrogen, silicon or oxygen

Matsubara

Bellotti

2017

Journal of Applied Physics

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This work presents an in-depth investigation of the properties of complexes composed of hydrogen, silicon or oxygen with carbon, which are major unintentional impurities in undoped GaN. This manuscript is a complement to our previous work on carbon-carbon and carbon-vacancy complexes. We have employed a first-principles method using Heyd-Scuseria-Ernzerhof hybrid functionals within the framework of generalized Kohn-Sham density functional theory. Two H-C, four Si-C and five O-C complexes in different charge states have been considered. After full geometry relaxations, formation energies, binding energies and both thermal and optical transition levels were obtained. The calculated energy levels have been systematically compared with the experimentally observed carbon related trap levels. Furthermore, we computed vibrational frequencies for selected defect complexes and defect concentrations were estimated in the low, mid and high carbon doping scenarios considering two different cases where electrically active defects: (a) only carbon and vacancies and (b) not only carbon and vacancies but also hydrogen, silicon and oxygen. We confirmed that CN is a dominant acceptor in GaN. In addition to it, substantial amount of SiGa − CN complex exists in a neutral form. This complex is a likely candidate for unknown form of carbon observed in undoped n-type GaN.PACS numbers: 61.72. 61.72.uj, 71.15.Mb, 71.55.Eq

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Local vibrational modes in Mg-doped gallium nitride

Cited by 70 publications

References 10 publications

Acceptor Neutralisation by Hydrogen in GaN and Wide Band Gap II-VI Materials

Acceptor Neutralisation by Hydrogen in GaN and Wide Band Gap II-VI Materials

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

A first-principles study of carbon-related energy levels in GaN. II. Complexes formed by carbon and hydrogen, silicon or oxygen

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