High Resolution X-ray Diffraction of GaN Grown on Sapphire Substrates

1996 ◽  
Vol 449 ◽  
Author(s):  
A. Saxler ◽  
M. A. Capano ◽  
W. C. Mitchel ◽  
P. Kung ◽  
X. Zhang ◽  
...  
Keyword(s):  
Metalorganic Chemical Vapor Deposition ◽  
Reciprocal Lattice ◽  
Chemical Vapor ◽  
Lattice Points ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Primary Mechanism

ABSTRACTX-ray rocking curves are frequently used to assess the structural quality of GaN thin films. In order to understand the information given by the line shape, we need to know the primary mechanism by which the curves are broadened. The GaN films used in this study were grown by low pressure metalorganic chemical vapor deposition (MOCVD) on (00•1) sapphire substrates. GaN films with both broad and very narrow (open detector linewidth of 40 arcseconds for the (00•2) GaN reflection) rocking curves are examined in this work. Reciprocal space maps of both symmetric and asymmetric reciprocal lattice points are used to determine that the cause of the broadening of GaN rocking curves is a limited in-plane coherence length.

Schottky I-V Characteristics of Au/Ni/GaN/SiNx nanonework/sapphire structures

2006 ◽  
Vol 955 ◽  
Author(s):  
Jinqiao Xie ◽  
Yi Fu ◽  
Hadis Morkoç
Keyword(s):  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Schottky Diodes ◽  
Chemical Vapor ◽  
Rocking Curve ◽  
X Ray ◽  
Sapphire Substrates ◽  
Control Samples

ABSTRACTGaN layers on sapphire substrates were grown by metalorganic chemical vapor deposition using in situ porous SiNx nano-network. Crystalline quality of epilayers was characterized by X-ray rocking curve scans, and the full width at hall maximum values for (002) and (102) diffractions were improved from 252 arc sec and 405 arc sec, respectively, in control samples to 216 arc sec and 196 arc sec when SiNx was used. Ni/Au Schottky diodes (SDs) were fabricated and the SD performance was found to be critically dependent on the SiNx coverage (fewer and farther the pores the better the results) which is consistent with the trends of XRD and photoluminescence data. A 1.13eV barrier height was achieved when 5min SiNx layer was used compared with 0.78 eV without any SiNx nanonetwork. Furthermore, the breakdown voltage improved from 76 V to 250V when SiNx nanonetwork was used in otherwise identical structures.

The Effect of a GaN Nucleation Layer on GaN Film Properties Grown by Metalorganic Chemical Vapor Deposition

1995 ◽  
Vol 395 ◽  
Author(s):  
W. Van Der Stricht ◽  
I. Moerman ◽  
P. Demeester ◽  
J.A Crawley ◽  
E.J. Thrush ◽  
...  
Keyword(s):  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
X Ray Diffraction ◽  
Film Properties ◽  
Double Crystal ◽  
Nucleation Layer ◽  
X Ray ◽  
Sapphire Substrates ◽  
Gan Film

ABSTRACTIn this paper GaN films are examined, which are grown on basal plane (0001) sapphire substrates. Growth is performed in a novel type of vertical rotating disk reactor. Results on the effect of a GaN nucleation layer on the properties of the overgrown GaN epilayer are presented. Characterisation includes surface morphology studies, DC X-ray diffraction and optical characterisation. Best film quality so far has a double crystal X-ray half width of 85 arcsec at approximately 1 μm thickness.

scholarly journals Material Properties of GaN Films Grown on SiC/SOI Substrate

2008 ◽  
Vol 600-603 ◽  
pp. 1313-1316
Author(s):  
Zhe Chuan Feng ◽  
C. Tran ◽  
Ian T. Ferguson ◽  
J.H. Zhao
Keyword(s):  
Vapor Deposition ◽  
Material Properties ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Metalorganic Chemical ◽  
Deposition Technology

Material properties of GaN thin films grown on 3C-SiC/semiconductor-on-insulator (SOI) substrate, by metalorganic chemical vapor deposition technology, are studied by X-ray diffraction, photoluminescence and Raman scattering, with data indicating the high quality of GaN films. Our results have shown that SiC/SOI structures obtained by carbonization have the potential to serve as useful substrates for GaN growth.

Strain Property Studies of GaN:Mg Films Grown by MOCVD

2005 ◽  
Vol 475-479 ◽  
pp. 1697-1700
Author(s):  
Qian Feng ◽  
Yue Hao
Keyword(s):  
Strain Distribution ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Raman Shift ◽  
X Ray Diffraction ◽  
Strain Property ◽  
X Ray ◽  
Mg Doping ◽  
Sapphire Substrates ◽  
Inhomogeneous Strain

The influence of Mg doping on structural and strain properties in GaN layers grown on sapphire substrates by metalorganic chemical vapor deposition was studied by means of high resolution X-ray diffraction and Raman scattering. The results showed that the disorder of GaN films aggravated and the quality reduced as Mg doping rate increasing. However, according to the theoretic calculation, the compressive stress determined by the Raman shift of the E2 mode was not due to the substitution of Mg atoms for Ga. Furthermore, the SEM measurements indicated that some Mg atoms substituted Ga to become acceptors, while most of them existed as Mg interstitials(Mgi) and aggregated at defects and dislocation, hence a great deal of cracks are introduced during decreasing temperature process for inhomogeneous strain distribution.

AlxGa1-xN-Based Materials and Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Kung ◽  
A. Saxler ◽  
D. Walker ◽  
X. Zhang ◽  
R. Lavado ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Bragg Reflectors ◽  
X Ray Diffraction ◽  
Chemical Vapor Deposition Growth ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Dimensional Electron Gas ◽  
P Type

ABSTRACTWe present the metalorganic chemical vapor deposition growth, n-type and p-type doping and characterization of AlxGa1-xN alloys on sapphire substrates. We report the fabrication of Bragg reflectors and the demonstration of two dimensional electron gas structures using AlxGa1-xN high quality films. We report the structural characterization of the AlxGa1-xN / GaN multilayer structures and superlattices through X-ray diffraction and transmission electron microscopy. A density of screw and mixed threading dislocations as low as 107 cm-2 was estimated in AlxGa1-xN / GaN structures. The realization of AlxGa1-xN based UV photodetectors with tailored cut-off wavelengths from 365 to 200 nm are presented.

Real-Time Composition And Thickness Control Techniques In A Metalorganic Chemical Vapor Deposition Process

1995 ◽  
Vol 406 ◽  
Author(s):  
M. S. Gaffneyt ◽  
C. M. Reavesl ◽  
A. L Holmes ◽  
R. S. Smith ◽  
S. P. DenBaars
Keyword(s):  
Chemical Vapor Deposition ◽  
Real Time ◽  
Vapor Deposition ◽  
Metalorganic Chemical Vapor Deposition ◽  
Chemical Vapor ◽  
Normal Operation ◽  
Growth Monitoring ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metalorganic Chemical

AbstractMetalorganic chemical vapor deposition (MOCVD) is a process used to manufacture electronic and optoelectronic devices that has traditionally lacked real-time growth monitoring and control. We have developed control strategies that incorporate monitors as real-time control sensors to improve MOCVD growth. An analog control system with an ultrasonic concentration monitor was used to reject bubbler concentration disturbances which exist under normal operation, during the growth of a four-period GaInAs/InP superlattice. Using X-ray diffraction, it was determined that the normally occurring concentration variations led to a wider GaInAs peak in the uncompensated growths as compared to the compensated growths, indicating that closed loop control improved GaInAs composition regulation. In further analysis of the X-ray diffraction curves, superlattice peaks were used as a measure of high crystalline quality. The compensated curve clearly displayed eight orders of satellite peaks, whereas the uncompensated curve shows little evidence of satellite peaks.

scholarly journals Исследование этапов превращения кремния в карбид кремния в процессе атомного замещения методами полного внешнего отражения рентгеновских лучей и рентгеновской дифрактомерии

2022 ◽  
Vol 64 (3) ◽  
pp. 326
Author(s):  
С.А. Кукушкин ◽  
А.В. Осипов ◽  
Е.В. Осипова ◽  
В.М. Стожаров
Keyword(s):  
Structural Quality ◽  
Total External Reflection ◽  
X Rays ◽  
Reflection Method ◽  
X Ray Diffraction ◽  
Modified Technique ◽  
Substitution Method ◽  
X Ray ◽  
Sic Films

X-ray diffraction and total external reflection of X-rays (X-ray reflectometry) methods were used to study the successive stages of synthesis of epitaxial SiC films on Si (100) X-ray diffraction and total external X-ray reflection (XRD) methods were used to study successive stages of synthesis of epitaxial SiC films on Si (100) surfaces, (110) and (111) surfaces by the atom substitution method. The data on the transformation evolution of (100) surfaces were studied, (110) and (111) Si, into SiC surfaces. A comparative analysis of the X-ray structural quality of the SiC layers grown on Si by the atom substitution method with the quality of SiC layers grown by Advanced Epi by the standard CVD method. A modified technique for the total outer X-ray reflection method, based on measurements of the intensity of the reflected X-rays using a special parabolic mirror. It is shown that the method of total external reflection method makes it possible to obtain important information about the degree of surface roughness of SiC layers, the evolution of their crystal structure and plasmon energy in the process of Si to SiC conversion.

Protein crystals can be incommensurately modulated

2008 ◽  
Vol 41 (3) ◽  
pp. 600-605 ◽  
Author(s):  
Jeffrey J. Lovelace ◽  
Cameron R. Murphy ◽  
Lee Daniels ◽  
Kartik Narayan ◽  
Clarence E. Schutt ◽  
...  
Keyword(s):  
Diffraction Pattern ◽  
Reciprocal Lattice ◽  
Lattice Points ◽  
Chemical Crosslinking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic State ◽  
Orientation Matrix ◽  
Aperiodic Crystals ◽  
Future Work

For a normal periodic crystal, the X-ray diffraction pattern can be described by an orientation matrix and a set of three integers that indicate the reciprocal lattice points. Those integers determine the spacing along the reciprocal lattice directions. In aperiodic crystals, the diffraction pattern is modulated and the standard periodic main reflections are surrounded by satellite reflections. The successful indexing and refinement of the main unit cell andqvector usingTWINSOLVE, developed by Svensson [(2003). Lund University, Sweden], are reported here for an incommensurately modulated, aperiodic crystal of a profilin:actin complex. The indexing showed that the modulation is along thebdirection in the crystal, which corresponds to an `actin ribbon' formed by the crystal lattice. Interestingly, the transition to the aperiodic state was shown to be reversible and the diffraction pattern returned to the periodic state during data collection. It is likely that the protein underwent a conformational change that affected the neighbouring profilin:actin molecules in such a way as to produce the observed modulation in the diffraction pattern. Future work will aim to trap the incommensurately modulated crystal state, for example using cryocooling or chemical crosslinking, thus allowing complete X-ray data to be collected.

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