Improvement of crystalline quality of N-polar AlN layers on c-plane sapphire by low-pressure flow-modulated MOCVD

Takeuchi, Misaichi; Shimizu, Hirofumi; Kajitani, Ryo; Kawasaki, Koji; Kumagai, Yoshinao; Koukitu, Akinori; Aoyagi, Yoshinobu

doi:10.1016/j.jcrysgro.2006.10.140

Cited by 53 publications

(55 citation statements)

References 15 publications

(15 reference statements)

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“…(4) Physical vapor deposition techniques including sputtering Yoshino et al, 2000) and pulsed-laser deposition (Ryu et al, 2000), which is particularly amenable to complex chemistries . (5) Chemical vapor deposition (CVD) techniques, particularly metalorganic CVD (Kim and Lee, 2007;Takeuchi et al, 2007), that are well suited to singlecrystal fabrication.…”

Section: Streaming Assumptions Characteristics References Notesmentioning

confidence: 99%

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

2011

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This article reviews acoustic microfluidics: the use of acoustic fields, principally ultrasonics, for application in microfluidics. Although acoustics is a classical field, its promising, and indeed perplexing, capabilities in powerfully manipulating both fluids and particles within those fluids on the microscale to nanoscale has revived interest in it. The bewildering state of the literature and ample jargon from decades of research is reorganized and presented in the context of models derived from first principles. This hopefully will make the area accessible for researchers with experience in materials science, fluid mechanics, or dynamics. The abundance of interesting phenomena arising from nonlinear interactions in ultrasound that easily appear at these small scales is considered, especially in surface acoustic wave devices that are simple to fabricate with planar lithography techniques common in microfluidics, along with the many applications in microfluidics and nanofluidics that appear through the literature.

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Section: Streaming Assumptions Characteristics References Notesmentioning

confidence: 99%

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

2011

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“…8 However, the development of various growth methods has improved the epitaxial quality of AlN in recent years. These include alternating (e.g., MEE), [9][10][11][12][13][14][15] combination of simultaneous and alternating supply of precursors (e.g., modified MEE), 16 direct and hightemperature growth, [16][17][18] substrate pre-treatment (e.g., nitridation), 19,20 two-step LT-AlN BL and HT growth, 15,[21][22][23] multiple-step V/III growth, 18,24 precursor preflow, 25 and so on. However, despite the improvement in the surface morphology and structural quality of AlN, the existence of in-plane rotation domain as exhibited by SAGB is still observed regardless of growth method.…”

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“…26 While TMA preflow 25 and the LT-AlN BL with pre-nitridation 21 seem promising in-situ methods to eliminate the rotation domain, the influence of substrate's surface structure on its formation/elimination is not yet investigated in detail. The fragmentary understanding of the influence of surface structure is evident after the substrate is being subjected to thermal cleaning prior to AlN growth, 11,14,16,18,21,24 or the lack thereof. 10,13,15,22,25 Therefore, in this paper, we study the influence of the surface structure of sapphire substrate on the crystalline quality of AlN.…”

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confidence: 99%

“…In fact, a lot of AlN growth optimizations have been performed on such condition and yet, there was no observation of SAGB or hardly any mention if at all. The reason could be due to the weakening 11,14,26 This could be the reason why the growth interruption by V/III ratio not only resulted in dislocation bending or coalescence, but also the elimination of domain structure. 18,24 Moreover, the insertion of an intermediate layer after LT-AlN BL could have also eliminated the rotation domain.…”

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Influence of surface structure of (0001) sapphire substrate on the elimination of small-angle grain boundary in AlN epilayer

2015

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AlN epilayers were grown on (0001) sapphire substrates by metal-organic vapor phase epitaxy, and the influence of the substrate’s surface structure on the formation of in-plane rotation domain is studied. The surface structure is found to change with increasing temperature under H2 ambient. The ML steps of sapphire substrate formed during high-temperature (HT) thermal cleaning is found to cause the formation of small-angle grain boundary (SAGB). To suppress the formation of such structure, the use of LT-AlN BL technique was demonstrated, thereby eliminating the SAGB. The BL growth temperature (Tg) is also found to affect the surface morphology and structural quality of AlN epilayer. The optical emission property by cathodoluminescence (CL) measurement showed higher emission intensity from AlN without SAGB. The LT-AlN BL is a promising technique for eliminating the SAGB.

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“…Consequently they exhibit rough surface morphology because the growth rate significantly depends on the polarity. Moreover, the polarity of the layers grown on c-plane sapphire is sensitive to the presurface treatment and the succeeding growth conditions [6]. Controlling both the defect and the polarity is a key issue in getting high-quality AlN layers on sapphire.…”

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Polarity control of AlN by poling in the crystal growth

Ota

Inushima

2011

Phys. Status Solidi C

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We present a new technique for controlling the polarity of AlN grown by metal‐organic chemical vapor deposition on sapphire. We apply electric field along the c‐axis throughout the crystal growth process and Al‐ or N‐polarity AlN is obtained according to the direction of the electric field.It turns out that the polarization of pyroelectric AlN can be changed by the external field applied at the initial growth stage. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Improvement of crystalline quality of N-polar AlN layers on c-plane sapphire by low-pressure flow-modulated MOCVD

Cited by 53 publications

References 15 publications

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Influence of surface structure of (0001) sapphire substrate on the elimination of small-angle grain boundary in AlN epilayer

Polarity control of AlN by poling in the crystal growth

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