Deep traps determining the non-radiative lifetime and defect band yellow luminescence in n-GaN

Polyakov, A. Y.; Smirnov, N. B.; Yakimov, E. B.; Тарелкин, С. А.; Turutin, Andrei V.; Shemerov, I. V.; Pearton, S. J.; Bae, Kang; Lee, In Hwan

doi:10.1016/j.jallcom.2016.06.297

Cited by 32 publications

(28 citation statements)

References 33 publications

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“…Compared to the properties of deep levels in conventional HVPE FS-GaN crystals, the fingerprints of electronic states, which indicate a trap density and capture cross section, embedded in the Si-based FS-GaN are comparable 19–22 . (See Table 2) Furthermore, this is also comparable to the characteristics of the deep levels in the GaN layers grown using metalorganic chemical vapour deposition (MOCVD) 23–25 . Notwithstanding HVPE with a high growth rate, which can cause a deterioration of crystal quality in the GaN layers, the properties of deep trap levels in the Si-based HVPE FS-GaN exhibit relatively nondegraded characteristics, compared to those of the preexisting GaN films.…”

Section: Resultssupporting

confidence: 67%

First observation of electronic trap levels in freestanding GaN crystals extracted from Si substrates by hydride vapour phase epitaxy

Lee

Ahn

et al. 2019

Sci Rep

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The electronic deep level states of defects embedded in freestanding GaN crystals exfoliated from Si substrates by hydride vapour phase epitaxy (HVPE) is investigated for the first time, using deep level transient spectroscopy (DLTS). The electron traps are positioned 0.24 eV (E1) and 1.06 eV (E2) below the conduction band edge, respectively. The capture cross sections of E1 and E2 are evaluated to be 1.65 × 10 −17 cm 2 and 1.76 × 10 −14 cm 2 and the corresponding trap densities are 1.07 × 10 14 cm −3 and 2.19 × 10 15 cm −3 , respectively. The DLTS signal and concentration of the electronic deep levels are independent of the filling pulse width, and the depth toward the bottom of the sample, evidenced by the fact that they are correlated to noninteracting point defects. Furthermore, Photoluminescence (PL) measurement shows green luminescence, suggesting that unidentified point defects or complex, which affect the optical characterisitics, exhibit. Despite the Si-based materials, the freestanding GaN exhibits deep level characteristics comparable to those of conventional freestanding GaN, suggesting that it is a desirable material for use in the next generation optoelectronic devices with the large-scalibilityand low production costs.

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Section: Resultssupporting

confidence: 67%

First observation of electronic trap levels in freestanding GaN crystals extracted from Si substrates by hydride vapour phase epitaxy

Lee

Ahn

et al. 2019

Sci Rep

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“…EBIC measurements were performed using a field-emission scanning electron microscope (SEM) (JSM-6490, Jeol, Japan). [29][30][31] Preliminary results of deep trap and SEM measurements are described in Ref. 20.…”

Section: Methodsmentioning

confidence: 99%

“…The first step is to develop methods that allow the experimental determination of the diffusion lengths. Previously, we demonstrated for the case of another wide-bandgap material with short diffusion lengths, GaN, [28][29][30] that this can be obtained using EBIC. Combined with DLTS and ODLTS results for variously grown GaN films, this allowed assignment of the major deep electron traps that serve as lifetime killers in this material.…”

Section: Introductionmentioning

confidence: 99%

Diffusion length of non-equilibrium minority charge carriers in β-Ga2O3 measured by electron beam induced current

Yakimov

Polyakov

Smirnov

et al. 2018

Journal of Applied Physics

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The spatial distribution of electron-hole pair generation in b-Ga 2 O 3 as a function of scanning electron microscope (SEM) beam energy has been calculated by a Monte Carlo method. This spatial distribution is then used to obtain the diffusion length of charge carriers in high-quality epitaxial Ga 2 O 3 films from the dependence of the electron beam induced current (EBIC) collection efficiency on the accelerating voltage of a SEM. The experimental results show, contrary to earlier theory, that holes are mobile in b-Ga 2 O 3 and to a large extent determine the diffusion length of charge carriers. Diffusion lengths in the range 350-400 nm are determined for the as-grown Ga 2 O 3 , while processes like exposing the samples to proton irradiation essentially halve this value, showing the role of point defects in controlling minority carrier transport. The pitfalls related to using other popular EBIC-based methods assuming a point-like excitation function are demonstrated. Since the point defect type and the concentration in currently available Ga 2 O 3 are dependent on the growth method and the doping concentration, accurate methods of diffusion length determination are critical to obtain quantitative comparisons of material quality.

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“…In GaN such centers efficiently capture holes to their level near E v +1 eV but are inefficient in capturing electrons. [21][22][23] Since the equilibrium concentrations of such defects are expected to be high 20,21 this could provide an efficient non-radiative recombination channel, handicapping the internal quantum efficiency (IQE) of LEDs. Moreover, the presence of these (and other) defects, even if they have not developed into fully fledged SRH centers but selectively trap one type of charge carrier, can contribute to a de-crease of injection efficiency and to buildup potential fluctuations and localization effects similar to those created by In fluctuations.…”

mentioning

confidence: 99%

Deep Electron and Hole Traps in Electron-Irradiated Green GaN/InGaN Light Emitting Diodes

Lee

Polyakov

Smirnov

et al. 2017

ECS J. Solid State Sci. Technol.

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Deep electron and hole trap spectra and electroluminescence (EL) efficiency of green multi-quantum-well (MQW) GaN/InGaN light emitting diodes were measured before and after 6 MeV electron irradiation. Starting with a fluence of 5 × 10 15 cm −2 , electron irradiation increased the concentration of existing electron traps with levels at E c −0.5 eV and introduced new electron traps with levels near E c −1 eV. The latter are the well known radiation defects formed in the GaN barriers of the GaN/InGaN MQW region. The degradation of the EL efficiency after irradiation correlates with changes of the E c −0.5 eV and E c −1 eV electron trap density, suggesting these are effective non-radiative recombination centers. By sharp contrast, the concentration of the dominant hole traps with levels near E v +0.45 eV decreased after, which eliminates these from the role of Shockley-Read-Hall defects actively participating in recombination.

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Deep traps determining the non-radiative lifetime and defect band yellow luminescence in n-GaN

Cited by 32 publications

References 33 publications

First observation of electronic trap levels in freestanding GaN crystals extracted from Si substrates by hydride vapour phase epitaxy

First observation of electronic trap levels in freestanding GaN crystals extracted from Si substrates by hydride vapour phase epitaxy

Diffusion length of non-equilibrium minority charge carriers in β-Ga2O3 measured by electron beam induced current

Deep Electron and Hole Traps in Electron-Irradiated Green GaN/InGaN Light Emitting Diodes

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