Transition between wurtzite and zinc-blende GaN: An effect of deposition condition of molecular-beam epitaxy

Shi, Bo‐Rong; Xie, Mingyu; Wu, Huasheng; Wang, Naiyan; Tong, S. Y.

doi:10.1063/1.2360916

Cited by 47 publications

(21 citation statements)

References 22 publications

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“…Third, the catalyst introduces a triple phase line GaN-GaNi-vapor, and as described by Glas et al for WZ GaAs NWs [34], preferential nucleation at this location could reverse whether ZB or WZ formation is favorable. Fourth, the formation of SFs could also originate from a lower surface mobility of adatoms at the NW tip, which could then be trapped at ZB sites [35][36][37]. This is consistent with the reduction of the SF density which was observed as the growth temperature was increased.…”

Section: Crystal Structuresupporting

confidence: 72%

Direct comparison of catalyst-free and catalyst-induced GaN nanowires

et al. 2010

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GaN nanowires have been grown by molecular beam epitaxy either catalyst-free or catalyst-induced by means of Ni seeds. Under identical growth conditions of temperature and Ⅴ/Ⅲ ratio, both types of GaN nanowires are of wurtzite structure elongated in the Ga-polar direction and are constricted by M-plane facets. However, the catalyst-induced nanowires contain many more basal-plane stacking faults and their photoluminescence is weaker. These differences can be explained as effects of the catalyst Ni seeds.

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Section: Crystal Structuresupporting

confidence: 72%

Direct comparison of catalyst-free and catalyst-induced GaN nanowires

et al. 2010

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“…The diffraction pattern on every point along a scan line can be obtained, giving the crystallographic information from a very small area. [4]. It is unlikely that the phase transition is related to diffusion of Ge into the epilayer as the SIMS analysis previously showed little sign of Ge diffusion [2].…”

Section: Contributedmentioning

confidence: 95%

Structural features in GaN grown on a Ge(111) substrate

Zhang

McAleese

Xiu

et al. 2008

Phys. Status Solidi (c)

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Using electron microscopy, structural characterisation has been carried out on a GaN epilayer grown directly on a Ge(111) substrate using plasma assisted molecular beam epitaxy (PAMBE) without any intermediate buffer layers. It was determined that a defect with a triangular shape, initially observed with optical microscopy, is essentially a faceted void in the Ge extending from the interface into the substrate. Both hexagonal and cubic phase GaN were observed in the epilayer which may be due to temperature variation during growth. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…The shape of the temperature dependence obtained for the bandgap width for the studied epitaxial GaN layers can be explained by an increase in the plasma shift in E g with an increase in threshold concentration of nonequilibrium charge carriers as the temperature rises. It is also possible that the there is some effect on the behavior of E g (T) from cubic phase GaN [20]. For the temperature dependence of the square of the interband optical transition matrix element with no selection rule for the wave vector, two regions can be arbitrarily distinguished (Fig.…”

Section: Resultsmentioning

confidence: 98%

Interband transition matrix element and temperature dependence of the lasing threshold for GaN laser structures

et al. 2007

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UDC 621.378.35By comparing experimental and theoretical radiative recombination spectra, we have determined the values of the square of the matrix element for interband optical transitions ⏐M⏐ 2 in epitaxial GaN at different temperatures T. The data obtained were used to analyze the mechanism for the temperature dependence of the lasing threshold for a GaN laser. In the experiments, we used epitaxial layers of GaN with a wurtzite crystal structure, grown on Al 2 O 3 (0001) substrates and excited by a focused beam from a nitrogen laser. We have shown that the spontaneous emission spectra near the lasing threshold of a GaN laser are consistent with the model of optical interband transitions not obeying a selection rule for the electron wave vector. As we have established, the parameter ⏐M⏐ 2 practically does not vary for T = 300-470 K: 5.4⋅10 -73 kg 2 ⋅m 5 /sec 2 . Further increase in the temperature leads to an exponential fall-off in ⏐M⏐ 2 down to 3.4⋅10 -73 kg 2 ⋅m 5 /sec 2 at T ≈ 520 K. Such behavior of ⏐M⏐ 2 as a function of temperature correlates with the sudden increase in the nonradiative recombination rate at T > 470 K, and may be connected with a change in the recombination mechanisms in the active layer of the GaN laser in the high temperature region.Key words: gallium nitride, lasing threshold, matrix element, radiative and nonradiative recombination.Introduction. Wide-gap semiconductor materials based on GaN are of great interest for developers of various optoelectronic devices. Researchers have directed significant efforts toward design of high-efficiency laser structures emitting in the blue region of the spectrum at elevated temperatures of the active medium [1-3]. Today the optical properties of such structures are being intensively studied [4][5][6][7][8][9]. Nevertheless, many physical processes observed in the active layers of GaN-based emitters remain insufficiently studied. This includes in particular the phenomenon of the rapid rise in the threshold pump rate R p of epitaxial GaN laser structures as the temperature T of the medium increases above some critical value T b [4]. As shown in [5,6], this type of variation in R p (T) is mainly explained by the features of the temperature variation of the radiative (R sp ) and nonradiative (Q) recombination rates. However, this approach gives only general ideas about the possible reason for the strong temperature dependence of the lasing threshold in GaN semiconductor lasers. For a detailed explanation of the mechanism for the rapid rise in R p (T), we need to take into account additional parameters more precisely characterizing the optical transition rate.In this paper, we present a method for determining the square of the interband optical transition matrix element ⏐M⏐ 2 in the active layer of a semiconductor laser. The method is based on comparing the experimental and theoretical spectra for radiative recombination at the lasing threshold. The values of ⏐M⏐ 2 obtained were used for analysis of the mechanism of radiative recombination in epitaxial ...

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Transition between wurtzite and zinc-blende GaN: An effect of deposition condition of molecular-beam epitaxy

Cited by 47 publications

References 22 publications

Direct comparison of catalyst-free and catalyst-induced GaN nanowires

Direct comparison of catalyst-free and catalyst-induced GaN nanowires

Structural features in GaN grown on a Ge(111) substrate

Interband transition matrix element and temperature dependence of the lasing threshold for GaN laser structures

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