Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

Lefèbvre, Pierre; Albert, Steven; Ristić, Jelena; Fernández-Garrido, Sergio; Grandal, J.; Sánchez-García, M.Á.; Calleja, E.

doi:10.1016/j.spmi.2012.05.001

Cited by 17 publications

(25 citation statements)

References 26 publications

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“…As mentioned in Sec. III, Raman scattering shows the electron concentration in our nanowires to be below 10 17 16 , and 10 17 cm −3 (blue, green, and red solid lines, respectively). These values are reliable only above the black dashed line, which thus shows the lower limit for a given set of φ and N D for which the surface potential can be considered to be parabolic.…”

Section: Surface-induced Parabolic Potentialmentioning

confidence: 89%

“…Indirect evidence for the coexistence of neutral and ionized donors even at low temperatures has been obtained in the experiments reported in Refs. [8,17].…”

Section: Binding Energy Of Donors In the Presence Of Internal Elecmentioning

confidence: 99%

“…For example, they modify the radiative decay rate of excitons [8,17] and possibly enhance the coupling between * corfdir@pdi-berlin.de free and bound excitons with profound consequences for the exciton decay dynamics [18,19]. In (In,Ga)N/GaN nanowire heterostructures, the interplay between the polarization and surface potentials may lead to a radial separation of electron and holes, resulting in a dramatic decrease of the internal quantum efficiency in the blue spectral range [20].…”

Section: Introductionmentioning

confidence: 99%

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Sub-meV linewidth in GaN nanowire ensembles: Absence of surface excitons due to the field ionization of donors

et al. 2014

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We observe unusually narrow donor-bound exciton transitions (400 µeV) in the photoluminescence spectra of GaN nanowire ensembles grown on Si(111) substrates at very high (>850 ∘C) temperatures. The spectra of these samples reveal a prominent transition of excitons bound to neutral Si impurities which is not observed for samples grown under standard conditions. Motivated by these experimental results, we investigate theoretically the impact of surface-induced internal electric fields on the binding energy of donors by a combined Monte Carlo and envelope function approach. We obtain the ranges of doping and diameter for which the potential is well described using the Poisson equation, where one assumes a spatially homogeneous distribution of dopants. Our calculations also show that surface donors in nanowires with a diameter smaller than 100 nm are ionized when the surface electric field is larger than about 10 kV/cm, corresponding to a doping level higher than 2×1016cm−3. This result explains the experimental observation: since the (D+,X) complex is not stable in GaN, surface-donor-bound excitons do not contribute to the photoluminescence spectra of GaN nanowires above a certain doping level, and the linewidth reflects the actual structural perfection of the nanowire ensemble

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Section: Surface-induced Parabolic Potentialmentioning

confidence: 89%

“…Indirect evidence for the coexistence of neutral and ionized donors even at low temperatures has been obtained in the experiments reported in Refs. [8,17].…”

Section: Binding Energy Of Donors In the Presence Of Internal Elecmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sub-meV linewidth in GaN nanowire ensembles: Absence of surface excitons due to the field ionization of donors

et al. 2014

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“…Furthermore, it is generally 7 accepted that adsorbed oxygen results in a decrease of the carrier lifetime that can be measured by PL. 12,13 Under illumination, we observe a variation of the NW conductivity Δσ. Keeping in mind that the conductivity is given by σ = enμ, where e is the electronic charge, n is the carrier density, and μ is the carrier mobility, a change in conductivity, Δσ = e(μΔn+nΔμ), can occur either due to change in the carrier concentration, Δn, or to a change in the carrier mobility, Δμ .…”

mentioning

confidence: 91%

Environmental sensitivity of n-i-n and undoped single GaN nanowire photodetectors

Гонзалез-Посада

Songmuang

Hertog

et al. 2013

Applied Physics Letters

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International audienceIn this work, we compare the photodetector performance of single nearly defect-free undoped and n-i-n GaN nanowires (NWs). Undoped NWs present a dark current three orders of magnitude lower than n-i-n structures, about ten times lower gain, and a strong dependence of the measurement environment. In vacuum, undoped NWs react with an increase of their responsivity, accompanied by stronger nonlinearities and persistent photoconductivity effects. This behavior is attributed to the unpinned Fermi level at the m-plane NW sidewalls, which enhances the role of surface states in the photodetection dynamics. In the air, adsorbed oxygen accelerates the carrier dynamics at the price of reducing the photoresponse. In contrast, in n-i-n NWs, the Fermi level pinning at the contact regions limits the photoinduced sweep of the surface band bending, hence reducing the environment sensitivity and preventing persistent effects even in vacuum

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“…Lefebvre et al have reported a strong influence on the PL intensity of bare GaN NWs under different atmospheres. 13 In particular, 20 The growth parameters applied for NWs on diamond are equivalent to those on Si substrate. However, GaN NW growth on diamond is characterized by a slightly thicker diameter of the NWs compared to NWs on Si due to an enhanced lateral growth (SEM images in Fig.…”

Section: Resultsmentioning

confidence: 99%

Surface passivation and self-regulated shell growth in selective area-grown GaN–(Al,Ga)N core–shell nanowires

et al. 2017

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The large surface-to-volume ratio of GaN nanowires implicates sensitivity of the optical and electrical properties of the nanowires to their surroundings. The implementation of an (Al,Ga)N shell with a larger band gap around the GaN nanowire core is a promising geometry to seal the GaN surface. We investigate the luminescence and structural properties of selective area-grown GaN-(Al,Ga)N core-shell nanowires grown on Si and diamond substrates. While the (Al,Ga)N shell allows a suppression of yellow defect luminescence from the GaN core, an overall intensity loss due to Si-related defects at the GaN/(Al,Ga)N interface has been observed in the case of Si substrates. Scanning transmission electron microscopy measurements indicate a superior crystal quality of the (Al,Ga)N shell along the nanowire side facets compared to the (Al,Ga)N cap at the top facet. A nucleation study of the (Al,Ga)N shell reveals a pronounced bowing of the nanowires along the c-direction after a short deposition time which disappears for longer growth times. This is assigned to an initially inhomogeneous shell nucleation. A detailed study of the proceeding shell growth allows the formulation of a strain-driven self-regulating (Al,Ga)N shell nucleation model.

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Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

Cited by 17 publications

References 26 publications

Sub-meV linewidth in GaN nanowire ensembles: Absence of surface excitons due to the field ionization of donors

Sub-meV linewidth in GaN nanowire ensembles: Absence of surface excitons due to the field ionization of donors

Environmental sensitivity of n-i-n and undoped single GaN nanowire photodetectors

Surface passivation and self-regulated shell growth in selective area-grown GaN–(Al,Ga)N core–shell nanowires

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