Influence of different types of threading dislocations on the carrier mobility and photoluminescence in epitaxial GaN

Shi, J. Y.; Lan, Yu; Wang, Y. Z.; Zhang, G. Y.; Zhang, H.

doi:10.1063/1.1465531

Applied Physics Letters

2002

DOI: 10.1063/1.1465531

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Influence of different types of threading dislocations on the carrier mobility and photoluminescence in epitaxial GaN

J. Y. Shi

Yu Lan

Y. Z. Wang

et al.

Abstract: High-resolution x-ray diffraction has been used to analyze the type and density of threading dislocations in a series (0001)-oriented GaN epitaxial film. Photoluminescence (PL) and carrier mobility of the films are measured at room temperature. The intensities of both the band edge (3.42 eV) peak and yellow luminescence (YL) are strongly related to the threading dislocation density of the GaN films. But different types of dislocations show different relationship with the intensities of PL and YL. The fundament… Show more

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Cited by 74 publications

(50 citation statements)

References 15 publications

(22 reference statements)

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“…However, it has only recently been realised that the edge and screw nature of the threading dislocations has an influence on the band edge and yellow photoluminescence [2]. In their seminal transmission electron microscopy and high-resolution X-ray diffraction study, Metzger et al [3] demonstrated clearly the connection of threading edge dislocations to in-plane mosaic and threading screw dislocations to out-of-plane mosaic.…”

mentioning

confidence: 98%

Direct, Independent Measurement of Twist and Tilt Mosaic as a Function of Thickness in Epitaxial GaN

Lafford¹,

Parbrook

Tanner

2002

phys. stat. sol. (c)

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The twist and tilt mosaics in a series of GaN epitaxial films grown by metal-organic vapour-phase epitaxy (MOVPE) have been measured directly by grazing incidence in-plane X-ray diffraction and in the standard symmetric high resolution setting. The variation in tilt mosaic with layer thickness fits well the model of Ayers. A similarly good fit to the same function for the twist mosaic dependence on epilayer thickness is found, indicating that the ratio of edge to screw dislocations remains constant for all films.

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mentioning

confidence: 98%

Direct, Independent Measurement of Twist and Tilt Mosaic as a Function of Thickness in Epitaxial GaN

Lafford¹,

Parbrook

Tanner

2002

phys. stat. sol. (c)

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“…5 Highresolution x-ray diffraction studies of GaN layers have indicated that both carrier mobility and the intensity of photoluminescence are strongly related to defects. 6 It was also observed that a phase transformation from wurtzite ͑WZ͒ to rock-salt structure can be induced by high pressure in GaN. 7 However for GaN nanostructures, surface stresses due to high surface-to-volume ratios are another factor that may lead to structural transitions.…”

mentioning

confidence: 99%

“…To study the size effect, rods with different cross-sectional diameters ͑d = 22. 6 lent semiconductor with significant ionic characteristics, 13 a set of interatomic pair potentials 14 consisting of a long-range Coulombic part and a short-range part is used to describe the Ga-Ga, N-N and Ga-N interatomic interactions. The calculation of long-range Coulomb force uses direct summation without any cutoff in order to accurately describe chargecharge interactions.…”

mentioning

confidence: 99%

Surface transformation and inversion domain boundaries in gallium nitride nanorods

Xiao

Wang

et al. 2009

Applied Physics Letters

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Phase transformation and subdomain structure in ͓0001͔-oriented gallium nitride ͑GaN͒ nanorods of different sizes are studied using molecular dynamics simulations. The analysis concerns the structure of GaN nanorods at 300 K without external loading. Calculations show that a transformation from wurtzite to a tetragonal structure occurs along ͕0110͖ lateral surfaces, leading to the formation of a six-sided columnar inversion domain boundary ͑IDB͒ in the ͓0001͔ direction of the nanorods. This structural configuration is similar to the IDB structure observed experimentally in GaN epitaxial layers. The transformation is significantly dependent on the size of the nanorods. © 2009 American Institute of Physics. ͓doi:10.1063/1.3268467͔With a wide band gap, gallium nitride ͑GaN͒ promises superior performances for blue light-emitting diodes, 1 highpower sources, and optical data storage devices.2 Recent advances in the synthesis of one-dimensional nanostructures have brought forth possibilities for GaN to be used in more applications.3 Structural transformations and defects are subjects of active experimental and theoretical research for GaN, 4 because they lead to significant changes in physical and chemical properties and, therefore, affect applications. These transformations and defects can be caused by external or internal factors. For epitaxially grown GaN layers, because of the lack of a lattice and thermally matching substrate, they always contain large numbers of defects.5 Highresolution x-ray diffraction studies of GaN layers have indicated that both carrier mobility and the intensity of photoluminescence are strongly related to defects.6 It was also observed that a phase transformation from wurtzite ͑WZ͒ to rock-salt structure can be induced by high pressure in GaN. 7 However for GaN nanostructures, surface stresses due to high surface-to-volume ratios are another factor that may lead to structural transitions. Experimental observations and atomistic simulations show that structural reorientation can occur in metal ͑copper, silver, and gold͒ nanowires due to high surface-stresses. 8,9 This reorientation causes some of the face-centered-cubic metal nanowires to exhibit a shape memory and pseudoelasticity which are not possessed by corresponding bulk materials. 9 The microscopic details of structural transformations in nanostructures are, however, difficult to investigate through direct experimental observations. Atomistic simulations can play an important role in this regard. Recently, molecular dynamics ͑MD͒ simulations are carried out to analyze the atomistic structures of singlecrystal GaN nanotubes and the buckling behavior of GaN nanowires.10 Yet, the effect of surface-stresses on the structural transformation in GaN nanorods is still poorly understood and merit careful inspection. Here, MD simulations are carried out to investigate the surface transformation and defect formation in GaN nanorods. The analyses concern the equilibrium structure of GaN nanorods with lateral dimensions between 22.6-67.4 Å ...

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“…In particular, extremely high TDDs can drastically degrade the internal quantum efficiency [2,3], mobility [4] and the carrier concentration [5] in LEDs. Several methods of fabricating high-quality templates have been reported; for example, the use of AlN/AlGaN super lattices (SLs) grown with alternating gas-feeds [6], AlGaN templates deposited by epitaxial lateral overgrowth [7], and a combination of GaN/AlN SLs and AlGaN produced by alternating-source-feed epitaxy on SiC [8].…”

mentioning

confidence: 99%

Remarkable improvement in output power for an InAlGaN based ultraviolet LED by improving the crystalline quality of AlN/AlGaN templates

Takano

Fujikawa

Kondo

et al. 2008

Phys. Status Solidi (c)

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The use of quaternary InAlGaN is very attractive for the realization of commercially‐available low‐cost and high‐power ultraviolet light‐emitting diodes (UV‐LEDs), because highly‐efficient UV emission can be obtained from this material due to In‐segregation effects. We achieved remarkable improvements in output power from 340 nm‐band quaternary InAlGaN‐based UV‐LEDs and demonstrated high UV‐output power by using high‐quality AlN buffer templates on sapphire substrates. Threading dislocation densities (TDDs) for screw and edge‐type dislocations were 1×108cm–2 and 1×109cm–2, as observed from cross‐sectional transmission electron microscope (TEM) images. The output power of a 340 nm‐band UV‐LED was increased by approximately 7 times by reducing the full‐width‐at‐half‐maximum (FWHM) of the (10‐12) X‐ray ω‐scan rocking curve (XRC) from around 800 arcsec to 510 arcsec. As a result, we achieved a maximum output power of 7.1 mW under room‐temperature (RT) and continuous‐wave (CW) operation. From these results, we confirmed that the crystalline quality of AlN/AlGaN templates strongly affects the output power of UV‐LEDs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Influence of different types of threading dislocations on the carrier mobility and photoluminescence in epitaxial GaN

Cited by 74 publications

References 15 publications

Direct, Independent Measurement of Twist and Tilt Mosaic as a Function of Thickness in Epitaxial GaN

Direct, Independent Measurement of Twist and Tilt Mosaic as a Function of Thickness in Epitaxial GaN

Surface transformation and inversion domain boundaries in gallium nitride nanorods

Remarkable improvement in output power for an InAlGaN based ultraviolet LED by improving the crystalline quality of AlN/AlGaN templates

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