Comparison of the Microstructure of AlN Films Grown by MOCVD and by PLD on Sapphire Substrates

1996 ◽  
Vol 449 ◽  
Author(s):  
Yun-Xin Li ◽  
Lourdes Salamanca-Riba ◽  
V. Talyan ◽  
T. Venkatesan ◽  
C. Wongchigul ◽  
...  
Keyword(s):  
Low Density ◽  
Full Width ◽  
High Crystalline Quality ◽  
Rocking Curve ◽  
X Ray ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Film Substrate ◽  
Microscopy Images

ABSTRACT(0001) aluminium nitride thin films were grown epitaxially on (0001) Sapphire substrates by MOCVD at 1200° C and PLD at 800° C. Both films have the same epitaxial growth relationship: (0001)AlN//(0001)Sap, and the same in-plane relationship which shows a 30° rotation between A1N and Sapphire: [ 12 10]AlN//[0 110]Sap and [10 10]AlN //[ 2110]Sap. The full width at half maximum (FWHM) of x-ray rocking curve of the MOCVD A1N film was 0.16° and PLD A1N film was 0.2°. Films grown by both MOCVD and PLD showed high crystalline quality. HRTEM images showed that these films are single crystalline with very low density of defects.Dislocations in the film parallel to the film / substrate interface were observed in both A1N films. Atomic force microscopy images showed that the MOCVD films have flatter and larger terraces than the PLD films. The PLD technique for A1N growth needs to be improved further. But both films have a surface roughness of approximately 100nm.

Ultra-Smooth ZnO Buffer Layers on (001) Sapphire

1997 ◽  
Vol 482 ◽  
Author(s):  
A. J. Drehman ◽  
S.-Q. Wang ◽  
P. W. Yip
Keyword(s):  
Buffer Layers ◽  
Zno Films ◽  
Potential Candidate ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Electrical Resistivities

AbstractUsing off-axis reactive rf sputtering, we have grown extremely smooth, nearly epitaxial, (001) oriented ZnO films on c-axis sapphire substrates. Atomic Force Microscopy was used to determine that these films are extremely smooth, having an rms roughness of only a few tenths of a nanometer. Based on high resolution x-ray diffraction (HXRD), the ZnO is highly oriented, with a rocking curve width of less than 400 arc seconds for the (006) diffraction peak, and only somewhat larger for the (112) reflection. HXRD Phi scans show that the ZnO (112) reflection is rotated in the a-b plane by 30 degrees from the sapphire (113) direction. These two measurements indicate excellent in-plane orientation. We are investigating the use of these buffer layers for subsequent GaN growth. Electrical resistivities of the films exceeded 100 kΩ-cm making ZnO a potential candidate as an insulating buffer layer.

Investigation Of Nucleation And Initial Stage Of Gan Growth By Atomic Force Microscopy And X-Ray Diffraction

1997 ◽  
Vol 482 ◽  
Author(s):  
P. W. Yip ◽  
S.-Q. Wang ◽  
A. J. Drehman ◽  
L. D. Zhu ◽  
P. E. Norris
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Morphology ◽  
Deposition Temperature ◽  
Yellow Luminescence ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Initial Stage

AbstractThe nucleation and initial stage of GaN growth on sapphire was investigated by atomic force microscopy, X-ray diffraction and photoluminescence. A 15 to 30 nm thick GaN buffer layer deposited at proper conditions was extremely smooth and nearly amorphous. Proper post deposition annealing resulted in the buffer crystallized. The buffer layer deposition temperature, thickness and annealing time and temperature must be coordinated. Low deposition temperature and/or insufficient annealing of the buffer results in a GaN wafer which has fine spiking surface morphology with an RMS of 3.4 nm for 1.4 μm wafer, strong yellow luminescence and wide xray rocking curve FWHM. High deposition temperature, longer crystallization time, and a low growth rate results in a wafer which exhibits strong band edge luminescence without noticeable yellow luminescence, and a narrow (002) diffraction rocking curve. However, the surface morphology exhibits well developed hexagonal feature with RMS roughness of 14.3 nm for a 570 nm thick layer. X-ray rocking curve analysis revealed buffer crystallization, domain coalescence and alignment process. The FWHM of the ω–scan of GaN (101) diffraction was 1700–2000 arc seconds for 200–1400 nm wafers which indicates that the twist of the domains is not changing much with the growth.

Gallium Nitride Growth Using Diethylgallium Chloride as an Alternative Gallium Source

1998 ◽  
Vol 537 ◽  
Author(s):  
Ling Zhang ◽  
Rong Zhang ◽  
Marek P. Boleslawski ◽  
T.F. Kuech
Keyword(s):  
Growth Conditions ◽  
Rocking Curve ◽  
X Ray ◽  
Force Microscopy ◽  
Organic Vapor ◽  
Atomic Force ◽  
Curve Line ◽  
Metal Organic ◽  
Increasing Temperature ◽  
Trimethyl Gallium

AbstractMetal organic vapor phase epitaxy (MOVPE) of GaN has been carried out using diethyl gallium chloride (DEGaCI) and ammonia. The growth rate and efficiency of the DEGaCl-based growth decreases with increasing temperature when compared to trimethyl gallium (TMG)-based growth under similar conditions. Both low temperature buffer and the high temperature GaN layers were grown using the DEGaCI-NH3 precursor combination on the basal plane of sapphire and compared to similar structures grown using TMG and NH3. DEGaCl-based growth reveals an improved growth behavior under identical growth conditions to the conventional TMGa and ammonia growth. X-ray, Hall, and atomic force microscopy (AFM) measurements have been carried out on these samples providing a direct comparison of materials properties associated with these growth precursors. For the DEGaCl-based growth, the x-ray rocking curve line width, using the (0002) reflection, is as low as 300 arcsec on a 2.5-micron thick film. A RMS surface roughness of ∼0.5nm measured over a 10x10 micron area.

Epitaxial growth of PbTiO3 thin films on (001) SrTiO3 from solution precursors

1995 ◽  
Vol 10 (3) ◽  
pp. 680-691 ◽  
Author(s):  
Andreas Seifert ◽  
Fred F. Lange ◽  
James S. Speck
Keyword(s):  
Thin Films ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
Amorphous Precursor ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Heat Treated ◽  
Film Substrate

A mixed alkoxide liquid precursor was used to form epitaxial PbTiO3 thin films by spin-coating on cubic (001) SrTiO3 substrates. The films were heat-treated at temperatures between 380 °C/1 h and 800 °C/1 h. X-ray diffraction, atomic force microscopy, scanning and transmission electron microscopy were used to characterize the microstructure of the films and to evaluate the epitaxial phenomena. At ∼400 °C/1 h, a polycrystalline, metastable Pb-Ti fluorite crystallizes from the pyrolyzed amorphous precursor. At slightly higher temperatures (∼420 °C/1 h), the thermodynamically stable phase with the perovskite structure epitaxially nucleates at the film/substrate interface. A small number of epitaxial grains grow through the film toward the surface and consume the nanocrystalline fluorite grains. Coarsening of the perovskite grains leads to a reduction in mosaic spread during further heating. Pores, which concurrently coarsen with grain growth, produce a pitted surface as they disappear from within the film. At 800 °C/1 ha dense epitaxial PbTiO3 film with a smooth surface is observed. Parameters governing the formation of a- and c-domains are discussed as well as the small tilts of the domain axes away from the substrate normal.

Characterization of single-crystal sapphire substrates by X-ray methods and atomic force microscopy

2011 ◽  
Vol 56 (3) ◽  
pp. 456-462 ◽  
Author(s):  
I. A. Prokhorov ◽  
B. G. Zakharov ◽  
V. E. Asadchikov ◽  
A. V. Butashin ◽  
B. S. Roshchin ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Single Crystal ◽  
X Ray ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Single Crystal Sapphire ◽  
Ray Methods

BaTiO3 Waveguides on MgO Buffered-Sapphire Single Crystals

1999 ◽  
Vol 597 ◽  
Author(s):  
Judit G. Lisoni ◽  
M. Siegert ◽  
C. H. Lei ◽  
C. L. Jia ◽  
J. Schubert ◽  
...  
Keyword(s):  
Optical Waveguides ◽  
Ferroelectric Thin Film ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
Rocking Curve ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Good Crystalline Quality

AbstractWithin our program to develop ferroelectric thin film optical waveguides, we have studied the growth of epitaxial waveguides BaTiO3 on r-plane sapphire substrates with a MgO buffer layer. The films were prepared by pulsed laser deposition (PLD). Their structural properties were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), Rutherford backscattering (RBS) in random and channeling (RBS-c) configuration and atomic force microscopy (AFM). They displayed good crystalline quality, characterized by an RBS-c minimum yield of about 4–6%, a full width at half maximum (FWHM) of the XRD rocking curve measurement of the BaTiO3(200) reflection of 0.32° and a rms roughness of 1.2 nm in a film of ∼ 1.0 μm thickness. The epitaxial relationship was found to be BaTiO3(100) // MgO(100) // A12O3(1102). The refractive index, the birefringence and the optical losses have been measured.

Multivariable study on homoepitaxial diamond growth using isotopically enriched carbon-13 gas mixtures

2009 ◽  
Vol 24 (2) ◽  
pp. 493-498 ◽  
Author(s):  
Gopi K. Samudrala ◽  
Yogesh K. Vohra
Keyword(s):  
Microwave Plasma ◽  
Chemical Vapor ◽  
Nitrogen Vacancy ◽  
Diamond Growth ◽  
Plasma Chemical ◽  
Rocking Curve ◽  
X Ray ◽  
Plasma Chemical Vapor Deposition ◽  
Force Microscopy ◽  
Atomic Force

We report our observations on the homoepitaxial diamond growth by microwave plasma chemical vapor deposition (MPCVD) experiments on Type Ib diamond substrates conducted by varying three independent variables. In a feed gas mixture of H2, N2, O2, and 13CH4, the amount of nitrogen was varied in the range of 0 to 4000 ppm, the amount of methane was varied from 2% CH4/H2 to 6% CH4/H2, and the substrate temperature was varied in the range of 850 to 1200 °C. We used isotopically enriched carbon-13 methane gas as the source of carbon in the plasma to clearly distinguish the grown diamond layer from the underlying substrate using Raman spectroscopy. The x-ray rocking curve measurements confirmed the homoepitaxial nature of the deposited layers with a slight increase in the full width at half-maximum for sample grown with the highest nitrogen content in the plasma. Optical and atomic force microscopy revealed dramatic changes in surface morphology with variation in each parameter. The nitrogen incorporation in carbon-13 diamond layers was monitored through photoluminescence spectroscopy of nitrogen–vacancy complexes. A twentyfold increase in diamond growth rate was clearly achieved in this multivariable study.

Epitaxial Batio3 and Knbo3 Thin Films On Various Substrates for Optical Waveguide Applications

1996 ◽  
Vol 441 ◽  
Author(s):  
L. Beckers ◽  
W. Zander ◽  
J. Schubert ◽  
P. Leinenbach ◽  
Ch. Buchal ◽  
...  
Keyword(s):  
Optical Materials ◽  
Rutherford Backscattering Spectrometry ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
Rocking Curve ◽  
X Ray ◽  
Flat Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
Yield Values

AbstractTechnologically interesting optical materials such as BaTiO3 and KnbO3 are difficult to grow as single crystals of large dimensions. Thin film techniques can overcome this problem by synthesizing these materials on commercially available substrates. We demonstrate the deposition of single crystalline BaTiO3 and KnbO3 on MgO, SrTiO3 and buffered MgO substrates by Pulsed Laser Deposition (PLD). The samples are characterized by Rutherford Backscattering Spectrometry / Channeling (RBS/C), X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM). We found excellent crystalline quality, confirmed by RBS/C minimum yield values of 2 % and a FWHM of 0.36° of the BaTiO3(002) rocking curve. Even films of a few microns thickness have been grown without loss of crystalline perfection, and all films show very flat surfaces. The RMS roughness of a 950 nm BaTiO3 film was found to be 1.1 nm.

scholarly journals Gallium Nitride Growth Using Diethylgallium Chloride as an Alternative Gallium Source

1999 ◽  
Vol 4 (S1) ◽  
pp. 351-356
Author(s):  
Ling Zhang ◽  
Rong Zhang ◽  
Marek P. Boleslawski ◽  
T.F. Kuech
Keyword(s):  
Growth Conditions ◽  
Rocking Curve ◽  
X Ray ◽  
Force Microscopy ◽  
Organic Vapor ◽  
Atomic Force ◽  
Curve Line ◽  
Metal Organic ◽  
Increasing Temperature ◽  
Trimethyl Gallium

Metal organic vapor phase epitaxy (MOVPE) of GaN has been carried out using diethyl gallium chloride (DEGaCl) and ammonia. The growth rate and efficiency of the DEGaCl-based growth decreases with increasing temperature when compared to trimethyl gallium (TMG)-based growth under similar conditions. Both low temperature buffer and the high temperature GaN layers were grown using the DEGaCl-NH3 precursor combination on the basal plane of sapphire and compared to similar structures grown using TMG and NH3. DEGaCl-based growth reveals an improved growth behavior under identical growth conditions to the conventional TMGa and ammonia growth. X-ray, Hall, and atomic force microscopy (AFM) measurements have been carried out on these samples providing a direct comparison of materials properties associated with these growth precursors. For the DEGaCl-based growth, the x-ray rocking curve line width, using the (0002) reflection, is as low as 300 arcsec on a 2.5-micron thick film. A RMS surface roughness of ∼0.5nm measured over a 10×10 micron area.

scholarly journals Growth of High-Quality GaN Films on Epitaxial AlN/Sapphire Templates

2019 ◽  
Author(s):  
Xiejia
Keyword(s):  
Chemical Vapor ◽  
Organic Chemical ◽  
High Quality ◽  
Rocking Curve ◽  
Force Microscopy ◽  
Atomic Force ◽  
Low Dislocation Density ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition ◽  
Microscopy Images

High quality GaN films have been successfully grown on multi-AlN/sapphire templates by metal organic chemical vapor deposition system. The Hall mobility and the carrier concentration of 720 cm2/Vs and 6.7x1016 cm-3 at 300K, respectively, along with low dislocation density of 4.1x109 cm-2 have been achieved. The X-ray rocking curve full-width at half-maximum were 160 and 290 arcsec for (0004) and (20-24) reflection planes also obtained, respectively. Besides that, the atomic force microscopy images showed smooth surface morphology and a higher intensity near the band edge was also observed by photoluminescence measurement result.

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