Analysis of GaN/AlN buffer layers grown on sapphire substrates via statistical diffraction theory

2005 ◽  
Author(s):  
S.T. Mudie ◽  
K.M. Pavlov ◽  
M.J. Morgan ◽  
Y. Takeda ◽  
M. Tabuchi ◽  
...  
Keyword(s):  
Diffraction Theory ◽  
Buffer Layers ◽  
Sapphire Substrates ◽  
Aln Buffer

Comparative Study on MOCVD Growth of a-Plane GaN Films on r-Plane Sapphire Substrates Using GaN, AlGaN, and AlN Buffer Layers

2009 ◽  
Vol 38 (9) ◽  
pp. 1938-1943 ◽  
Author(s):  
J. N. Dai ◽  
Z. H. Wu ◽  
C. H. Yu ◽  
Q. Zhang ◽  
Y. Q. Sun ◽  
...  
Keyword(s):  
Comparative Study ◽  
Buffer Layers ◽  
Sapphire Substrates ◽  
Mocvd Growth ◽  
Aln Buffer

Atomic scale characterization of GaInN/GaN layers grown on sapphire substrates with low-temperature deposited AlN buffer layers

2002 ◽  
Vol 237-239 ◽  
pp. 1133-1138 ◽  
Author(s):  
M. Tabuchi ◽  
H. Kyouzu ◽  
Y. Takeda ◽  
S. Yamaguchi ◽  
H. Amano ◽  
...  
Keyword(s):  
Low Temperature ◽  
Atomic Scale ◽  
Buffer Layers ◽  
Sapphire Substrates ◽  
Scale Characterization ◽  
Aln Buffer

HALL EFFECT, MAGNETORESISTIVITY AND MAGNETIC PROPERTIES OF MgB2 THIN FILMS WITH AlN BUFFER LAYERS

2008 ◽  
Vol 22 (08) ◽  
pp. 991-996
Author(s):  
G. ILONCA ◽  
T. R. YANG ◽  
A. V. POP ◽  
P. BALINT ◽  
M. BODEA ◽  
...  
Keyword(s):  
Thin Films ◽  
Upper Critical Field ◽  
Buffer Layers ◽  
Temperature Dependent ◽  
Sapphire Substrates ◽  
Anisotropic Coefficient ◽  
Aln Buffer ◽  
Mgb2 Thin Films ◽  
Sputtering System

MgB 2 thin films were deposited at low temperature substrates, in situ, on c-plane sapphire substrates, with the aluminium nitride (AlN) buffer layers, using the multiple-target sputtering system. The magnetoresistivities were measured using dc-five probe method in applied magnetic field up to 9 Tesla. The upper critical field anisotropy, HC2(T) and irreversibility field H irr (T) versus temperature were determined. The Hall coefficients RH are slightly temperature dependent and positive in the normal state. The critical temperature of 30–32 K and critical current density of 106-107 A/cm 2 at 4.2 K were obtained. Using extracted data, the coherence length ξo, anisotropic coefficient γ and penetration depth λL were calculated.

Characterization of ALN buffer layers on (0001)-sapphire substrates

1998 ◽  
Vol 189-190 ◽  
pp. 282-286 ◽  
Author(s):  
Yves-Matthieu Le Vaillant ◽  
René Bisaro ◽  
Jean Olivier ◽  
Olivier Durand ◽  
Jean-Yves Duboz ◽  
...  
Keyword(s):  
Buffer Layers ◽  
Sapphire Substrates ◽  
Aln Buffer

Dislocation reduction with quantum dots in GaN grown on sapphire substrates by molecular beam epitaxy

2002 ◽  
Vol 722 ◽  
Author(s):  
David J. Smith ◽  
Daming Huang ◽  
Michael A Reshchikov ◽  
Feng Yun ◽  
T. King ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Aln Buffer

AbstractWe have investigated a novel approach for improving GaN crystal quality by utilizing a stack of quantum dots (QDs) in GaN grown on sapphire substrates by molecular beam epitaxy. The GaN films were grown on GaN/AlN buffer layers containing multiple QDs and characterized using x-ray diffraction, photoluminescence, atomic force microscopy, and transmission electron microscopy. The density of the dislocations in the films was determined by defect delineation wet chemical etching and atomic force microscopy. It was found that the insertion of a set of multiple GaN QD layers in the buffer layer effectively reduced the density of the dislocations in the epitaxial layers. As compared to a density of ∼1010cm-2in typical GaN films grown on AlN buffer layers, a density of ∼3×107cm-2was demonstrated in GaN films grown with the QD layers. Transmission electron microscopy observations confirmed termination of threading dislocations by the QD layers.

Polarity Control of GaN Films Grown by Metal Organic Chemical Vapor Deposition on (0001) Sapphire Substrates

2004 ◽  
Vol 831 ◽  
Author(s):  
Seiji Mita ◽  
Ramon Collazo ◽  
Raoul Schlesser ◽  
Zlatko Sitar
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Organic Chemical ◽  
Sapphire Substrates ◽  
Mixed Polarity ◽  
Metal Organic ◽  
Aln Buffer ◽  
Organic Chemical Vapor Deposition

ABSTRACTThe polarity control of GaN films grown on c-plane sapphire substrates by low pressure metal organic chemical vapor deposition (MOCVD) was achieved by using N2 as a diluent and transport gas. The type of polarity was governed by the substrate treatment prior to the GaN growth. N-face (-c) GaN films were only obtained by pre-nitridation of the sapphire substrate after a H2 anneal, while Ga-face (+c) GaN films were grown directly on the substrates or on properly annealed AlN buffer layers. In addition, GaN films on improperly annealed AlN buffer layers, that is, under- or over-annealed buffer layers, yielded films with mixed polarity. Smooth N-face GaN films with 2.5 nm RMS roughness, as determined by atomic force microscopy (AFM), were obtained with shorter nitridation times (less than 2 min). Wet chemical etching in an aqueous solution of potassium hydroxide (KOH) was used to determine the polarity type.

Nucleation and Growth of Gallium Nitride Films on Si and Sapphire Substrates Using Buffer Layers

1996 ◽  
Vol 423 ◽  
Author(s):  
N. R. Perkins ◽  
M. N. Horton ◽  
D. Zhi ◽  
R. J. Matyi ◽  
Z. Z. Bandic ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Defect Density ◽  
Deep Level ◽  
Growth Front ◽  
Nucleation And Growth ◽  
Buffer Layers ◽  
Initial Growth ◽  
X Ray ◽  
Sapphire Substrates ◽  
Aln Buffer

AbstractWe have investigated the nucleation and growth of gallium nitride (GaN) films on silicon and sapphire substrates using halide vapor phase epitaxy (HVPE). GaN growth was carried out on bare Si and sapphire surfaces, as well as on MOVPE-grown GaN buffer layers. HVPE growth on MOVPE GaN/AlN buffer layers results in lower defect densities as determined by x-ray than growth directly on sapphire. HVPE GaN films grown directly on sapphire exhibit strong near-edge photoluminescence, a pronounced lack of deep level-based luminescence, and x-ray FWHM values of 16 arcsec by an x-ray θ-2θ scan. The crystallinity of GaN films on sapphire is dominated by the presence of rotational misorientation domains, as measured by xray ω-scan diffractometry, which tend to decrease with increasing thickness or with the use of a homoepitaxial MOVPE buffer layer. The effect of increasing film thickness on the defect density of the epilayer was studied. In contrast, the HVPE growth of nitride films directly on silicon is complicated by mechanisms involving the formation of silicon nitrides and oxides at the initial growth front.

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