Growth of high-quality GaN films on epitaxial AlN/sapphire templates by MOVPE

Sakai, Masahiro; Ishikawa, Hiroyasu; Egawa, Takashi; Jimbo, Takashi; Umeno, Masayoshi; Shibata, Tomohiko; Asai, Keiichiro; Sumiya, S.; Kuraoka, Yoshitaka; Tanaka, Mitsuhiro; Oda, Osamu

doi:10.1016/s0022-0248(02)01573-7

Cited by 55 publications

(30 citation statements)

References 11 publications

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“…However, the image of sample A shows clearer and more ordered atomic growth steps than those of sample B. The smooth surface morphology of GaN grown on AlN template is also reported by many other researchers [2][3][4]. When the HT-AlN is used, the more flat surface of sample A indicates the enhancement of the two-dimensional (2D) growth of the GaN.…”

Section: Resultssupporting

confidence: 56%

“…Although there are many methods to obtain high quality GaN films, such as conventional two-step process, epitaxial lateral overgrowth (ELOG), maskless ELOG, and pendeoepitaxy (PE), it is still far from crystal perfection. Recently, a promising substrate, AlN template is used to grow high quality GaN films and high-performance devices by MOCVD [2][3][4]. Furthermore, LED grown on it shows better light power versus current (L-I) characteristics than that grown on sapphire substrate, especially under the high injection level [5].…”

Section: Introductionmentioning

confidence: 99%

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Improvement of crystal quality of GaN grown on AlN template by MOCVD using HT‐AlN interlayer

Tao

Chen

Zhi‐Jian

et al. 2009

Phys. Status Solidi (c)

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Two GaN samples, with and without high temperature (HT)‐AlN interlayer (labelled as sample A and B, respectively) grown by MOCVD on AlN template, were investigated by double‐crystal X‐ray diffraction (DC‐XRD), photoluminescence (PL), and atomic force microscope (AFM) measurements. It was found that the crystal quality of GaN could be greatly improved by the HT‐AlN interlayer. The full width at half maximum (FWHM) of (102) reflection in XRD rocking curve was narrower for sample A than that for sample B. However, the FWHMs of (002) reflections were almost the same for the two samples. In addition, the tilt degree which reflected screw dislocation density was almost the same, while the twist degree which reflected edge dislocation density changed from 0.214° to 0.152° when the HT‐AlN interlayer was used. Both the intensities of (102) reflection in XRD and band edge emission in PL for sample A were stronger too. In the AFM images, the atomic growth steps of sample A were clearer than those of sample B. According to the results of the in situ optical reflectivity spectra and the atomic force microscope (AFM) images, the above results were attributed to the three‐dimensional (3D) growth mode of the HT‐AlN interlayer. The HT‐AlN interlayer may work as a kind of “micro‐area” seed for epitaxial lateral overgrowth (ELOG) resulting in bending some dislocations. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Improvement of crystal quality of GaN grown on AlN template by MOCVD using HT‐AlN interlayer

Tao

Chen

Zhi‐Jian

et al. 2009

Phys. Status Solidi (c)

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“…1. Sakai and co-workers have measured that the room-temperature photoluminescence (PL) spectrum of the GaN film, grown on an AlN/template and on a sapphire substrate with LT-BL [1]. And they found that the intensity of YL of both film are almost the same.…”

Section: Measurementsmentioning

confidence: 99%

“…On the other hand, it was reported that high crystalline quality epitaxial AlN films grown on sapphire substrate at high temperature are promising template for GaN epitaxial growth [1]. The superior performance of GaNbased devices, high electron mobility transistor (HEMTs), grown on epitaxial AlN/sapphire template has also been shown [2][3][4].…”

mentioning

confidence: 99%

Trap states in n‐GaN grown on AlN/sapphire template by MOVPE

Ito

Yoshikawa

Watanabe

et al. 2008

Phys. Status Solidi (c)

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Using epitaxial AlN/sapphire templates, high crystalline quality GaN films are grown on them by metal organic chemical vapour deposition. The electron traps behaviour of these GaN films were observed by deep level transient spectroscopy (DLTS). Four distinct trap levels were ob‐served in both n‐GaN grown on AlN/sapphire template and on conventional low temperature buffer layer (LT‐BL)/sapphire. The magnitude the of the DLTS signal E1 and E2 were almost same. It suggests that E1 is not only associate with dislocation density but also other defect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…However, the GaN-based LED grown on sapphire using the LT-buffer layer usually shows a high density of threading dislocations because of a large mismatch in the lattice constant and the thermal expansion coefficients between the epilayer and the substrate [3]. Recently, high-quality GaN-based films were obtained on AlN/sapphire template instead of sapphire substrate [4,5]. In this study, the InGaN MQW LEDs were grown on AlN/sapphire template.…”

mentioning

confidence: 99%

InGaN multiple‐quantum‐well light‐emitting diodes on an AlN/sapphire template by metalorganic chemical vapor deposition

Zhang

Egawa²,

Liu

et al. 2003

phys. stat. sol. (c)

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An InGaN multiple-quantum-well (MQW) LED grown on AlN/sapphire template is reported. Comparing with the conventional LED on sapphire using a low temperature (LT) buffer layer, the LED on AlN/sapphire template shows better electrical and optical characteristics. The crystalline quality of the LED structure was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The zeroth, -first-and -second-order satellite peaks and the Pendellösung fringes can be seen clearly in (0004) XRD ω/2θ rocking curves for the LED on AlN/sapphire template. While, for the LED on sapphire, only the zeroth and -first-order satellite peaks can be seen. The full width at half maximum (FWHM) of GaN in (0004) ω scan is about 82.8 and 231.6 arcsec for the LED grown on AlN/sapphire template and sapphire, respectively. The dislocation density is 5 × 10 7 -3 × 10 8 cm -2 for the LED on AlN/sapphire template and 2-5 × 10 9 cm -2 for the LED on sapphire. The reverse leakage current of the LED on AlN/sapphire template is over one order of magnitude lower than that on sapphire due to the low threading dislocation density in the epilayer. The optical power of the LED on AlN/sapphire template increased sublinearly up to 300 mA injection current. 1 Introduction GaN-based electronic and optoelectronic devices have been extensively studied. The major obstacle to obtain high-quality nitride materials and devices is the lack of native substrates. At present, sapphire is the most commonly used substrate for GaN-based device growth. The most popular method of GaN-based epilayer growth is to use GaN or AlN films deposited at a low temperature (LT) on sapphire substrate as a buffer layer [1,2]. However, the GaN-based LED grown on sapphire using the LT-buffer layer usually shows a high density of threading dislocations because of a large mismatch in the lattice constant and the thermal expansion coefficients between the epilayer and the substrate [3]. Recently, high-quality GaN-based films were obtained on AlN/sapphire template instead of sapphire substrate [4,5]. In this study, the InGaN MQW LEDs were grown on AlN/sapphire template. Comparing with the conventional LED on sapphire using the LT-GaN buffer layer, the LED on AlN/sapphire template exhibits a better electrical and optical characteristic due to a low threading dislocation density in the epilayer and the high thermal conductive AlN layer.

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Growth of high-quality GaN films on epitaxial AlN/sapphire templates by MOVPE

Cited by 55 publications

References 11 publications

Improvement of crystal quality of GaN grown on AlN template by MOCVD using HT‐AlN interlayer

Improvement of crystal quality of GaN grown on AlN template by MOCVD using HT‐AlN interlayer

Trap states in n‐GaN grown on AlN/sapphire template by MOVPE

InGaN multiple‐quantum‐well light‐emitting diodes on an AlN/sapphire template by metalorganic chemical vapor deposition

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