Observation of optically detected magnetic resonance in GaN films

Glaser, E. R.; Kennedy, T. A.; Crookham, H.C.; Freitas, J. A.; Khan, M. Asif; Olson, D. T.; Kuznia, J. N.

doi:10.1063/1.110416

Cited by 49 publications

(23 citation statements)

References 10 publications

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“…Due to the weakness of the emissions on the high-energy side of the Γ5 in this configuration we can follow the Γ5L only up to 8 T. From there on a weak shoulder at lower energies due to emission from the Γ6 state can be observed from which a resolution of the splitting m this state is not possible. From the splitting of the Γ5T and Γ6 states at higher fields the conduction band g-value is determined for this configuration and amounts to 2.010.2, in good agreement with the results of other studies [8][9][10].…”

Section: Excitonic Fine Structuresupporting

confidence: 74%

Excitons and Phonons in GaN. Magnetooptical and Spatially Resolved Investigations

et al. 1998

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A. comprehensive study of the direct photoluminescence from free-exciton states in GaN using polarization-dependent and magnetooptical measurements is presented. We measured and identified fine-structure splittings in the n = 1 state of the A-exciton. From the magnetoluminescence data obtained in fields up to 15 T we determined the g-valfiies of the conduction and valence bands parallel and perpendicular to the c-axis. Self-organized hexagonal GaN pyramids of 5 μm width and covered by six {1101} side facets were investigated by spatially resolved cathodoluminescence and micro-Raman spectroscopy. Beside a narrow luminescence peak at 355 nm, originating from the 2 μm thick GaN layer, an additional broad luminescence band was observed from the GaN pyramids around a wavelength of 357 nm. A strong energy shift is found along the {1101} pyramidal facets and directly visualized by monochromatic cathodoluminescence images and line scans. In GaN epilayers grown on GaAs substrates a series of sharp modes in the range between 60 cm -1 and 250 cm -1 for temperatures below 100 K was found. The intensities of these modes increased drastically with decreasing temperature. Raman excitation spectra showed a maximum between 514.5 nm and 568 nm. A comparison of spatially resolved investigations with that of intentionally doped GaN epilayers showed that the in-diffusion of As from the substrate plays an important role. Raman spectra as a function of external fields, like magnetic field and hydrostatic pressure, gave additional information about the defect type and the underlying scattering mechanism.PACS numbers: 78.40.Fy, 78.45.+h (125) 126 A. Hoffmann et al.

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Section: Excitonic Fine Structuresupporting

confidence: 74%

Excitons and Phonons in GaN. Magnetooptical and Spatially Resolved Investigations

et al. 1998

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“…However, we like to point out that at lower resonance frequencies the DD resonance tends to exhibit higher g values 17 while with increasing frequency g decreases. 2,18,19 This behavior could be explained qualitatively by a nonvanishing zero field splitting of the DD resonance. However, a quantitative modeling of the experimental data in Table I shows that the simple addition of the magnetic field equivalent of the zero field splitting energy to the external magnetic field B 0 cannot completely account for the observed trend.…”

Section: A Optically Detected Magnetic Resonancementioning

confidence: 95%

“…The full width at half maximum ͑FWHM͒ of the DD resonance of 14 mT is similar to other reported values. 2,18 Since the FWHM was shown to be dependent on the excitation power density, 20 we have taken particular care to maintain identical excitation conditions between the measurements on Ga 14 N and Ga 15 N to avoid an influence of this effect on the present study. Due to this problem and the anisotropy of the acceptor resonances, the anisotropy of the DD linewidth could not be determined here.…”

Section: A Optically Detected Magnetic Resonancementioning

confidence: 99%

“…In contrast to these expectations, the deep defect exhibits a structureless, nearly Gaussian shaped line, with a width of Ϸ13 mT. 2 However, this line is assumed to be broadened by an unresolved hyperfine interaction since its width is found to be independent of the magnetic field used in the magnetic resonance experiments. 4,15 Therefore, substitution of 14 N by 15 N (I ϭ 1 2 , g n ϭ0.5664, n.a.ϭ0.366%͒ in principle should lead to changes in the line shape and thus could allow a more reliable microscopic assignment of the deep defect responsible for the yellow luminescence in GaN.…”

Section: Introductionmentioning

confidence: 98%

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Magnetic resonance investigations of defects in Ga14N and Ga15N

Bayerl

Reinacher

Angerer

et al. 2000

Journal of Applied Physics

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The influence of the nitrogen nuclear spin on the optically detected magnetic resonance and electron spin resonance signatures of the intrinsic shallow donor and a deep defect causing the characteristic yellow luminescence have been studied on wurtzite GaN epitaxial layers grown by plasma induced molecular beam epitaxy with isotopically pure N14 and N15. In particular, the linewidth of the deep defect signal is observed to be independent of the nitrogen isotope. The missing effect of the different nuclear spin properties of the N14 and N15 isotopes is discussed in view of current microscopic models for the yellow luminescence in GaN.

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“…The nature of the responsible residual donor has not been identified. It is often believed to be the N vacancy [1] [2] [3]. An EPR line with a halfwidth of about 0.5 mT was observed in nominally undoped, MOVPE-grown GaN and associated with the residual donor by correlated conductivity measurements [4].…”

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confidence: 99%

Optical Detection of Electron Nuclear Double Resonance on the Residual Donor in GaN

Koschnick

Michael

Spaeth

et al. 1996

MRS Internet j. nitride semicond. res.

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Optically detected electron nuclear double resonance (ODENDOR) was measured in the 2.2 eV 'yellow' luminescence band associated with the residual donor in n-type undoped GaN. The ODENDOR lines are due to gallium and show a quadrupole splitting which can be described with an axial tensor. The quadrupole parameter was estimated to be q( 69 Ga) = 1/2 Q zz = 0.22 MHz. A hyperfine interaction for 69 Ga of about 0.3MHz for the isotropic and of about 0.15 MHz for the anisotropic part was estimated from the width of the ODENDOR lines. It is tentatively suggested that a Ga interstitial is the residual donor. Application of gallium nitride for optical devices in the near UV region requires a control of the native and extrinsic defects. Undoped MOVPE-and HVPE-grown GaN layers have high residual n-type conductivities with typically 10 17 cm -3 to 10 19 cm -3 conduction electrons, exceeding the concentrations of impurities [1] [2]. This strongly suggests that the conductivity is due to native defects. The nature of the responsible residual donor has not been identified. It is often believed to be the N vacancy [1] [2] [3]. An EPR line with a halfwidth of about 0.5 mT was observed in nominally undoped, MOVPE-grown GaN and associated with the residual donor by correlated conductivity measurements [4]. The g values of the axial g tensor were determined to be g || = 1.9515 and g^ = 1.9483. But no conclusion could be drawn from the structureless EPR line on the nature of the donor which was also observed with optically detected EPR (ODEPR) via the so called 'yellow' luminescence band at 2.2 eV [5].We report on the first optically detected electron nuclear double resonance (ODENDOR) measurements on the residual donor in GaN. The nominally undoped GaN layers were grown on sapphire with MOVPE. The ODENDOR spectra were measured in the yellow luminescence as an intensity change of the ODEPR line of the donor at 1.5 K. ODENDOR was measured with cw microwave radiation and amplitude modulation (500 Hz) of the radio frequency [6].In Figure 1 (upper trace) the ODENDOR spectrum is shown for B || c. The relative ODENDOR effect with respect to the luminescence intensity was about 2 X 10 -5 . We found ODENDOR signals only between 7 MHz and 14 MHz. The recording time of the spectrum was about 10 hours because of the extremely weak signals. The ODENDOR effect vanished for the magnetic field outside the sharp donor ODEPR resonance. Since the ODENDOR lines are centered about the Larmor frequencies of the two Ga isotopes ( 69 Ga and 71 Ga with abundancies of 60.1% and 39.9%, respectively, both with I = 3/2) it can be concluded that they are due to Ga interactions. The angular dependence of the ODENDOR spectrum is shown in Figure 2. The crystal was rotated from B || c to B ^ c in steps of 15 degrees. The peak positions of the rather broad ODENDOR lines were determined by a deconvolution of each spectrum with Gaussian lines. The squares in Figure 2 represent the positions of the line peaks. The solid lines are calculated from the spin Hamilt...

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Observation of optically detected magnetic resonance in GaN films

Cited by 49 publications

References 10 publications

Excitons and Phonons in GaN. Magnetooptical and Spatially Resolved Investigations

Excitons and Phonons in GaN. Magnetooptical and Spatially Resolved Investigations

Magnetic resonance investigations of defects in Ga14N and Ga15N

Optical Detection of Electron Nuclear Double Resonance on the Residual Donor in GaN

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