Effect of low-temperature GaN buffer layer on the crystalline quality of subsequent GaN layers grown by MOVPE

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

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Morphology and surface reconstructions of m-plane GaN

MRS Proceedings ◽

10.1557/proc-743-l4.1 ◽

2002 ◽

Vol 743 ◽

Cited By ~ 1

Author(s):

C. D. Lee ◽

R. M. Feenstra ◽

J. E. Northrup ◽

L. Lymperakis ◽

J. Neugebauer

Keyword(s):

Molecular Beam Epitaxy ◽

Low Temperature ◽

Surface Morphology ◽

Buffer Layer ◽

Molecular Beam ◽

Structural Quality ◽

Surface Reconstructions ◽

Gan Buffer Layer

ABSTRACTM-plane GaN(1100) is grown by plasma assisted molecular beam epitaxy on ZnO(1100) substrates. A low-temperature GaN buffer layer is found to be necessary to obtain good structural quality of the films. Well oriented (1100) GaN films are obtained, with a slate like surface morphology. On the GaN(1100) surfaces, reconstructions with symmetry of c(2×2) and approximate “4×5” are found under N- and Ga-rich conditions, respectively. We propose a model for Ga-rich conditions with the “4×5” structure consisting of ≥ 2 monolayers of Ga terminating the GaN surface.

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Improvement of the crystalline quality of the ZnO epitaxial layer on a low-temperature grown ZnO buffer layer

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2004.02.111 ◽

2004 ◽

Vol 266 (4) ◽

pp. 505-510 ◽

Cited By ~ 48

Author(s):

J.F. Yan ◽

Y.M. Lu ◽

Y.C. Liu ◽

H.W. Liang ◽

B.H. Li ◽

...

Keyword(s):

Low Temperature ◽

Buffer Layer ◽

Epitaxial Layer ◽

Crystalline Quality ◽

Zno Buffer Layer

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Effects of the Nitridation Process of (0001) Sapphire on Crystalline Quality of InN Grown by RF-MBE

MRS Proceedings ◽

10.1557/proc-831-e4.2 ◽

2004 ◽

Vol 831 ◽

Cited By ~ 4

Author(s):

Daisuke Muto ◽

Ryotaro Yoneda ◽

Hiroyuki Naoi ◽

Masahito Kurouchi ◽

Tsutomu Araki ◽

...

Keyword(s):

Low Temperature ◽

Buffer Layer ◽

Buffer Layers ◽

Crystalline Quality ◽

Constant Independent ◽

Nitrogen Flux ◽

Sapphire Substrates ◽

Nitridation Process ◽

Flux Modulation

ABSTRACTThe effects of the nitridation process of (0001) sapphire on crystalline quality of InN were clearly demonstrated. The InN films were grown on NFM (nitrogen flux modulation) HT-InN or LT-InN buffer layers, which had been deposited on nitridated sapphire substrates. We found that low-temperature nitridation of sapphire is effective in improving the tilt distribution of InN films. Whereas the twist distribution remained narrow and almost constant, independent of nitridation conditions, when LT-InN buffer layers were used. The XRC-FWHM value of 54 arcsec for (0002) InN, the lowest reported to date, was achieved by using the LT-InN buffer layer and sapphire nitridation at 300°C for 3 hours.

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Structural Properties of Nitrides Grown by Omvpe on Sapphire Substrate

MRS Proceedings ◽

10.1557/proc-482-479 ◽

1997 ◽

Vol 482 ◽

Cited By ~ 1

Author(s):

H. Amano ◽

T. Takeuchi ◽

S. Yamaguchi ◽

S. Nitta ◽

M. Kariya ◽

...

Keyword(s):

Low Temperature ◽

Buffer Layer ◽

Structural Properties ◽

Sapphire Substrate ◽

Crystallization Process ◽

Free Standing ◽

In Situ Observations ◽

Gan Buffer Layer

AbstractCrystalline quality of nitrides on sapphire by OMVPE has been investigated. First, in-situ observations of the crystallization process of the low temperature deposited AIN buffer layer or GaN buffer layer on sapphire substrate have been performed. Small hexagonal mesas were formed from the sapphire to the surface and finally they formed a stacked structure. Secondly, a low temperature deposited buffer layer located between the high temperature grown GaN was found to reduce the etch pit density of GaN films. Thirdly, structural properties of Ga1−xInxN (0 ≤x≤0.21, and x= l) on GaN and GaInN/GaN MQWs on GaN have been characterized by Xray diffraction. Coherently grown GaInN showed almost the same twisting as the underlying GaN layer, while free standing InN showed large twisting. Thickness of the well layers in MQWs has been controlled within one monolayer preciseness, and the fluctuation of alloy composition has been controlled to within 2%

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Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD

Nanomaterials ◽

10.3390/nano11040928 ◽

2021 ◽

Vol 11 (4) ◽

pp. 928

Author(s):

Yong Du ◽

Zhenzhen Kong ◽

Muhammet Toprak ◽

Guilei Wang ◽

Yuanhao Miao ◽

...

Keyword(s):

High Temperature ◽

Buffer Layer ◽

Layer Thickness ◽

Growth Temperature ◽

Crystalline Quality ◽

Initial Growth ◽

Two Dimensional ◽

High Quality ◽

Reduced Pressure

This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski–Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it’s threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 °C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 × 107 cm−2). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.

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