Origin of defect-related photoluminescence bands in doped and nominally undoped GaN

Kaufmann, U.; Kunzer, M.; Obloh, H.; Maier, M.; Manz, C.; Ramakrishnan, A.; Šantić, Branko

doi:10.1103/physrevb.59.5561

Cited by 280 publications

(203 citation statements)

References 20 publications

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“…The donorlike discrete state at E D = E C − 0.37 eV, which is probably related to the N-vacancy defect, 30,31 and the acceptorlike state at E A = E V + 1.0 eV, which is related to the Ga vacancy, 32,33 were assumed ͓Fig. 3͑a͔͒.…”

Section: ͑6͒mentioning

confidence: 99%

Effects of interface states and temperature on the C-V behavior of metal/insulator/AlGaN/GaN heterostructure capacitors

Miczek

Mizue

Hashizume

et al. 2008

Journal of Applied Physics

179

141

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The impact of states at the insulator/AlGaN interface on the capacitance-voltage ͑C-V͒ characteristics of a metal/insulator/AlGaN/GaN heterostructure ͑MISH͒ capacitor was examined using a numerical solver of a Poisson equation and taking into account the electron emission rate from the interface states. A parallel shift of the theoretical C-V curves, instead of the typical change in their slope, was found for a MISH device with a 25-nm-thick AlGaN layer when the SiN x / AlGaN interface state density D it ͑E͒ was increased. We attribute this behavior to the position of the Fermi level at the SiN x / AlGaN interface below the AlGaN valence band maximum when the gate bias is near the threshold voltage and to the insensitivity of the deep interface traps to the gate voltage due to a low emission rate. A typical stretch out of the theoretical C-V curve was obtained only for a MISH structure with a very thin AlGaN layer at 300°C. We analyzed the experimental C-V characteristics from a SiN x / Al 2 O 3 / AlGaN/ GaN structure measured at room temperature and 300°C, and extracted a part of D it ͑E͒. The relatively low D it ͑ϳ10 11 eV −1 cm −2 ͒ in the upper bandgap indicates that the SiN x / Al 2 O 3 bilayer is applicable as a gate insulator and as an AlGaN surface passivant in high-temperature, high-power AlGaN/GaN-based devices.

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Section: ͑6͒mentioning

confidence: 99%

Effects of interface states and temperature on the C-V behavior of metal/insulator/AlGaN/GaN heterostructure capacitors

Miczek

Mizue

Hashizume

et al. 2008

Journal of Applied Physics

179

141

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“…Recently the YL in GaN has been found to exhibit a "blue-shift" with excitation intensity [10]. These and other experiments have suggested that YL is due to recombination between spatially separated donors and acceptors.…”

Section: Lbnl-44298mentioning

confidence: 95%

“…This is shown in Figure 2 The selectively-excited YL differs markedly from the E i > E g excited YL in its temperature dependence. One distinctive feature of the E i > E g YL noted in previous publications has been its lack of a dependence on temperature [10,18]. Figure 3 shows the selectively-excited YL spectra (E i = 2.471 eV) of a bulk sample measured for several temperatures (T) plotted on the same intensity scale.…”

Section: Lbnl-44298mentioning

confidence: 99%

“…Many competing explanations for its origin have been proposed, including transitions from shallow-donor to deep-acceptor [1,2,3,4,5,6], shallow-donor to deep-donor [7,8], and deep-donor to shallowacceptor [9], Even within these models, there are disagreements as to whether the YL originates from distant donor-acceptor pairs [10] (DAPs), or from localized DAP complexes [11].…”

Section: Lbnl-44298mentioning

confidence: 99%

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Selective excitation of the yellow luminescence of GaN

Colton

Teo

et al. 1999

Physica B: Condensed Matter

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The yellow luminescence of n-type GaN has been studied with selective excitation using a combination of Ar ion and dye lasers. Narrower structures whose peak energies follow the excitation photon energy over the width of the yellow luminescence have been observed. Unlike the yellow luminescence excited by above band gap excitations, these fine structures exhibits thermal activated quenching behavior. We propose that these fine structures are due to emission occurring at complexes of shallow donors and deep acceptors which can be resonantly excited by photons with energies below the band gap. The activation energy deduced from their intensity is that for delocalization of electrons out of the complexes. Our results therefore suggest that there is more than one recombination channel (usually assumed to be due to distant donor-acceptor pairs) to the yellow luminescence in GaN.

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“…The diagram is similar to those in Refs. [1] and [3], except that the difference in the energies of the EM and deeper donor states in our case needs to be much smaller than the 250 meV proposed in the former reference (this is since, in our case, the emission bands involving either the EM and or the deeper donors both lead to red emission). If we take the MM1 center to be Ga vacancy-related center, the scheme of Fig.…”

mentioning

confidence: 92%

Origin of the red luminescence in Mg-doped GaN

Zeng¹,

Aliev²,

Wolverson³

et al. 2006

Applied Physics Letters

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Optically-detected magnetic resonance (ODMR) and positron annihilation spectroscopy (PAS) experiments have been employed to study magnesium-doped GaN layers grown by metal-organic vapor phase epitaxy. As the Mg doping level is changed, the combined experiments reveal a strong correlation between the vacancy concentrations and the intensity of the red photoluminescence band at 1.8 eV. The analysis provides strong evidence that the emission is due to recombination in which electrons both from effective mass donors and from deeper donors recombine with deep centers, the deep centers being vacancy-related defects.Deep defects play a key role in the performance limits and aging effects of GaN-based light-emitting devices. They also lead to photoluminescence (PL) at energies well below the band-gap. For example, PL and opticallydetected magnetic resonance (ODMR) studies [1,2,3,4] have suggested that deep defects are responsible for the red (1.8 eV) luminescence band which is often observed in Mg-doped GaN and that the band is due to recombination emission in which vacancy-dopant complexes are involved [1,2]. However, this proposal was mainly based on indirect evidence and on previous experience of II -VI compounds, and further experimental confirmation is therefore needed. The present study involved the use of both ODMR and positron annihilation spectroscopy (PAS) on the same set of samples covering a range of Mg doping levels and we have established a correlation between the ODMR spectra (obtained by monitoring the red PL) and the PAS results.ODMR is well established as a means of investigating centers involved in recombination processes in semiconductors [5,6]. For a detailed description of the technique and our ODMR system, see Ref. [7]. The ODMR was carried out at 14 GHz with the specimen at 2K. The PL was excited with a UV argon-ion laser (363.8/351.1 nm). The microwaves were chopped at 605 Hz and changes in the PL intensity caused by magnetic resonance were monitored at this frequency as the magnetic field was slowly swept. PAS with a slow positron beam is an effective tool for the investigation of open volume defects such as neutral or negatively charged vacancies in semiconductor films. When positrons annihilate electrons in semiconductors the resulting gamma ray energy spectrum, peaked at 511 keV, is Doppler-broadened (since the electrons have a range of momenta). The annihilation linewidth is characterized by quantities S (W ), defined as the central (wing) fraction of the line. The value of S (W ) is characteristic of the material under study, but * Electronic address: d.wolverson@bath.ac.uk is generally higher (lower) when vacancies are present [8]. Measurements of S (W ) can thus be used to monitor vacancy concentrations. In the present work, singledetector Doppler-broadening PAS was performed using a magnetic transport positron beam system [9]. Positrons were implanted into the layers at energies in the range 0.1 -30 keV, corresponding to mean depths up to 1.5 nm.Details of the growth of the GaN:Mg sampl...

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Origin of defect-related photoluminescence bands in doped and nominally undoped GaN

Cited by 280 publications

References 20 publications

Effects of interface states and temperature on the C-V behavior of metal/insulator/AlGaN/GaN heterostructure capacitors

Effects of interface states and temperature on the C-V behavior of metal/insulator/AlGaN/GaN heterostructure capacitors

Selective excitation of the yellow luminescence of GaN

Origin of the red luminescence in Mg-doped GaN

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