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

Lafford, Tamzin; Parbrook, P. J.; Tanner, B. K.

doi:10.1002/pssc.200390109

Cited by 10 publications

(9 citation statements)

References 13 publications

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“…On the other hand, the same tendency of the tilt and the twist mosaic evolution versus epilayer thickness was found in Ref. [15]. In our case, where GaN layers are grown with the SiN treatment method, we noted that the thickness has a more pronounced effect on the twist mosaic than on the tilt as illustrated by its smaller slope.…”

Section: Resultssupporting

confidence: 81%

“…To check the reliability of the extrapolated values, GIIXD was used for the direct measurement of in plane twist mosaic. The method was successfully used in previous works [14][15][16]. Fig.…”

Section: Resultsmentioning

confidence: 98%

“…X-ray measurements were performed with high-resolution diffractometer equipped with a fourfold Ge (2 2 0) monochromator, delivering a pure CuKa 1 line of wavelength (l ¼ 0.154 nm). The GIIXD geometry was detailed in previous works [14][15][16]. Hall effect measurements were conducted by using the standard Van der Pauw configuration.…”

Section: Methodsmentioning

confidence: 99%

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Effect of thickness on structural and electrical properties of GaN films grown on SiN-treated sapphire

Bchetnia

Touré

Lafford³

et al. 2007

Journal of Crystal Growth

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 98%

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Effect of thickness on structural and electrical properties of GaN films grown on SiN-treated sapphire

Bchetnia

Touré

Lafford³

et al. 2007

Journal of Crystal Growth

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“…The crystallinity of the LED structures is analyzed in terms of the mosaic crystal model [9][10][11]. The broadening of symmetric, (00.2), (00.4), and (00.6), and asymmetric (10.2), (10.3), (10.4), (10.5), reflexes from GaN obtained by X-ray ω-scan has been used to estimate screw and edge threading dislocations density, respectively [11,12].…”

Section: Methodsmentioning

confidence: 99%

Indium‐free violet LEDs grown by HVPE

Usikov

Tsvetkov²,

Mastro³

et al. 2003

phys. stat. sol. (c)

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We report on first demonstration of violet light emitting diodes (LED) based on AlGaN/GaN/AlGaN heterostructures grown by hydride vapor phase epitaxy (HVPE). The unique aspects of this technological approach are (i) growth of Al-containing epitaxial material by HVPE and (ii) use of HVPE to fabricate submicron multi-layer epitaxial structures. The LEDs provide light emission at the wavelength of 415-420 nm that did not shift with forward current. External efficiency up to 2.5% is reached at the current of 20 mA. The brightness of LED lamp is as high as 400-500 mcd. This suggests HVPE as an alternative technique for growing AlGaN-based LED structures. Results of the LED modeling and characterization are discussed.1 Introduction Group-III nitrides are the attractive materials for application in visible and UV optoelectronic and electronic devices. Significant progress in GaN-based technology has been achieved with metal organic chemical vapor deposition (MOCVD). Blue, green and white light emitting diodes (LEDs), violet laser diodes, high electron mobility transistors, and ultra-violet photodiodes have recently been developed [1,2]. Historically, HVPE is one of the first techniques employed for GaN growth [3], which has been successfully used to fabricate thick, high-purity quasi-bulk substrates [4,5]. In addition, HVPE possess other advantages such as ability to (i) combine deposition of thick low-defect layers and thin device multi-layer structures in the same growth run and (ii) easily grow high-quality AlGaN layers in the whole composition range. Moreover, HVPE can provide low-impurity films, as it is a carbon-free process producing free HCl in a reactor, which getters metallic impurities. Thus, HVPE technique can be considered as an alternative cost-effective epitaxy technique for fabrication of AlGaN-based devices.TDI has previously reported on HVPE growth of submicron multi-layer AlGaN-based epitaxial structures for optoelectronic and electronic devices [6]. This paper is aimed at demonstrating the capability of HVPE to fabricate AlGaN/GaN/AlGaN violet LED structures. Optimization of the structure design by modeling and characteristics of the violet LEDs are discussed.

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“…However, previous X-ray studies have shown that there are ,5 times as many edge dislocations in this sample as screw dislocations. 31 It therefore must be concluded that -at least for the authors' particular imaging geometry -any contrast owing to the presence of edge dislocations is considerably less than that for screw dislocations. It is observed that small changes of tilt angle produce significant changes in the contrast of the observed dislocations.…”

Section: Resultsmentioning

confidence: 98%

Characterisation of nitride thin films by electron backscatter diffraction and electron channelling contrast imaging

Trager-Cowan¹,

Sweeney²,

Winkelmann³

et al. 2006

Materials Science and Technology

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In the present paper the authors describe the use of electron backscatter diffraction (EBSD) mapping and electron channelling contrast imaging (in the scanning electron microscope) to study tilt, strain, atomic steps and dislocations in epitaxial GaN thin films. Results from epitaxial GaN thin films and from a just coalesced epitaxial laterally overgrown GaN thin film are shown. From the results it is deduced that EBSD may be used to measure orientation changes of the order of 0·02° and strain changes of order 2 × 10−4 in GaN thin films. It is also demonstrated that channelling contrast in electron channelling contrast images may be used to image tilt, atomic steps and threading dislocations in GaN thin films. In addition the authors will consider the results of the first many-beam dynamical simulations of EBSD patterns from GaN thin films, in which the intensity distributions in the experimental patterns are accurately reproduced

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

Cited by 10 publications

References 13 publications

Effect of thickness on structural and electrical properties of GaN films grown on SiN-treated sapphire

Effect of thickness on structural and electrical properties of GaN films grown on SiN-treated sapphire

Indium‐free violet LEDs grown by HVPE

Characterisation of nitride thin films by electron backscatter diffraction and electron channelling contrast imaging

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