TEM and AFM studies of structural defects in α-GaN films

1995 ◽  
Vol 53 ◽  
pp. 456-457
Author(s):  
W. Qian ◽  
M. Skowronski ◽  
M. De Graef ◽  
G. Rohrer ◽  
K. Doverspike ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Defect Density ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Structural Defects ◽  
Group Iii ◽  
Transmission Electron ◽  
Potential Applications ◽  
Related Group

Interest in wide band-gap GaN and related group-III nitrides has grown recently due to their potential applications for short wavelength optoelectronic devices. One of the main obstacles for their application is the high density of defects formed during heteroepitaxy. Though important progress has been made by using a low temperature A1N buffer layer% recently reported films still contain a defect density (mainly threading dislocations) on the order of 1010 cm-2. This paper reports our current studies of structural defects in α-GaN thin films grown on a-plane (110) and c-plane (0001) sapphire substrates by organometallic vapor phase epitaxy (OMVPE). Atomic force microscopy (AFM), conventional and high resolution transmission electron microscopy (TEM) were used to investigate the nature and origin of these defects.Single crystal α-GaN films were grown using a low temperature A1N or GaN buffer layer in an inductively-heated, water cooled, vertical OMVPE reactor operated at 57 torr.

Growth and Characterizations of Gaas on Inp with Different Buffer Structures by Molecular Beam Epitaxy

1989 ◽  
Vol 148 ◽  
Author(s):  
Xiaoming Liu ◽  
Henry P. Lee ◽  
Shyh Wang ◽  
Thomas George ◽  
Eicke R. Weber ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Gaas Layer ◽  
Optical Quality ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Layer Structures ◽  
Gaas Films ◽  
Initial Deposition ◽  
Strained Layer Superlattices

ABSTRACTWe report the growth and characterizations of 31μm thick GaAs films grown on (100) InP substrates by MBE employing different buffer layer structures during the initial deposition. The buffer layer structures under study are: 1) GaAs layer grown at low temperature; 2) GaAs layer grown at low temperature plus two sets of In0.08Ga0.92As/GaAs strained layer superlattices (SLS) and 3) a transitional compositionally graded InxGal-xAs layer between the InP substrate and the GaAs film. After the buffer layer deposition, the growth was continued by conventionalMBE to a total thickness of 3μm for all samples. From the 77K photoluminescence (PL) measurement, it was found that the sample with SLS layers has the highest PL intensity and the narrowest PL linewidth. Cross-sectional transmission electron microscopy (TEM) studies showed that the SLS is effective in reducing the propagation of threading dislocations and explains the observed superior optical quality from the PL measurement.

scholarly journals Characterization of Gaas/Si/GaAs Heterointerfaces

1989 ◽  
Vol 148 ◽  
Author(s):  
Zuzanna Liliental-Weber ◽  
Raymond P. Mariella
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Defect Density ◽  
Si Substrate ◽  
Reverse Polarity ◽  
Si Substrates ◽  
Transmission Electron ◽  
Metal Semiconductor Metal

ABSTRACTTransmission electron microscopy of GaAs grown on Si for metal-semiconductor-metal photodetectors is presented in this paper. Two kinds of samples are compared: GaAs grown on a 15 Å Si epilayer grown on GaAs, and GaAs grown at low temperature (300°C) on Si substrates. It is shown that the GaAs epitaxial layer grown on thin Si layer has reverse polarity to the substrate (antiphase relation). Higher defect density is observed for GaAs grown on Si substrate. This higher defect density correlates with an increased device speed, but with reduced sensitivity.

Process simulation ofp -doping in GaN and related group III nitrides

2007 ◽  
Vol 4 (5) ◽  
pp. 1694-1697 ◽  
Author(s):  
Y. J. Zhou ◽  
Z. Q. Li ◽  
A. EL Boukili ◽  
Z. M. Simon Li
Keyword(s):  
Process Simulation ◽  
Group Iii Nitrides ◽  
Group Iii ◽  
Related Group

LOW-Temperature Epitaxial Growth of GaAs on Si Substrates by MBE

1992 ◽  
Vol 263 ◽  
Author(s):  
Ting-Yen Chiang ◽  
En-Huery Liu ◽  
Der-Hwa Yiin ◽  
Tri-Rung Yew
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Epitaxial Growth ◽  
Defect Density ◽  
Solution Treatment ◽  
Plan View ◽  
Si Substrates ◽  
Gaas On Si ◽  
Transmission Electron

ABSTRACTThis paper presents results of the low—temperature epitaxial growth of GaAs on Si substrates with orientation 1°—4° off (100) by molecular beam epitaxy (MBE). The epitaxial growth ·is carried out on Si wafers subjected to HF solution treatment by “spin-etch” technique before the wafer is transferred to the entry chamber of MBE system. Methods used for reducing defect density in the epitaxial layers are proposed. The characterization techniques include cross-sectional transmission electron microscopy (XTEM), plan-view transmission electron microscopy, scanning electron microscopy (S EM), and double crystal X-ray diffraction (DCXRD). Epitaxial films with a full width at half—maximum (FWHM) of about 310 arcsec measured by DCXRD are obtained without annealing.-

scholarly journals Growth of Crack-Free thick AlGaN Layer and its Application to GaN-Based Laser Diode

2000 ◽  
Vol 5 (S1) ◽  
pp. 452-458
Author(s):  
I. Akasaki ◽  
S. Kamiyama ◽  
T. Detchprohm ◽  
T. Takeuchi ◽  
H. Amano
Keyword(s):  
Buffer Layer ◽  
Laser Diode ◽  
Lattice Mismatch ◽  
Molar Fraction ◽  
Vertical Direction ◽  
Thick Layer ◽  
Group Iii Nitrides ◽  
Alloy Layer ◽  
Field Pattern ◽  
Group Iii

In the field of group-III nitrides, hetero-epitaxial growth has been one of the most important key technologies. A thick layer of AlGaN alloy with higher AlN molar fraction is difficult to grow on sapphire substrate, because the alloy layer is easily cracked. It is thought that one cause of generating cracks is a large lattice mismatch between an AlGaN and a GaN, when AlGaN is grown on the underlying GaN layer. We have achieved crack-free Al0.07Ga0.93N layer with the thickness of more than 1μm using underlying Al0.05Ga0.95N layer. The underlying Al0.05Ga0.95N layer was grown directly on sapphire by using the low-temperature-deposited buffer layer (LT-buffer layer). Since a lattice mismatch between the underlying Al0.05Ga0.95N layer and upper Al0.07Ga0.93N layer is relatively small, the generation of cracks is thought to be suppressed. This technology is applied to a GaN-based laser diode structure, in which thick n-Al0.07Ga0.93N cladding layer grown on the Al0.05Ga0.95N layer, improves optical confinement and single-robe far field pattern in vertical direction.

scholarly journals Improvement of Crystalline Quality of Group III Nitrides on Sapphire Using Low Temperature Interlayers

1999 ◽  
Vol 4 (S1) ◽  
pp. 870-877 ◽  
Author(s):  
H. Amano ◽  
M. Iwaya ◽  
N. Hayashi ◽  
T. Kashima ◽  
M. Katsuragawa ◽  
...  
Keyword(s):  
Low Temperature ◽  
Epitaxial Growth ◽  
Vapor Phase ◽  
Group Iii Nitrides ◽  
Crystalline Quality ◽  
Structural Quality ◽  
Group Iii

In organometallic vapor phase epitaxial growth of group III nitrides on sapphire, insertion of a low temperature interlayer is found to improve crystalline quality of AlxGa1−xN layer with x from 0 to 1. Here the effects of the low temperature deposited GaN or AlN interlayers on the structural quality of group III nitrides is discussed.

Structural Defects and Critical Electric Field in 3C-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 431-434 ◽  
Author(s):  
Michael A. Capano ◽  
A.R. Smith ◽  
Byeung C. Kim ◽  
E.P. Kvam ◽  
S. Tsoi ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Electric Field ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Chemical Vapor ◽  
Structural Defects ◽  
X Ray ◽  
Transmission Electron ◽  
Current Voltage ◽  
P Type

3C-SiC p-type epilayers were grown to thicknesses of 1.5, 3, 6 and 10 μm on 2.5° off-axis Si(001) substrates by chemical vapor deposition (CVD). Silane and propane were used as precursors. Structural analysis of epilayers was performed using transmission electron microscopy (TEM), high-resolution x-ray diffractometry (HRXRD), and Raman spectroscopy. TEM showed defect densities (stacking faults, twins and dislocations) decreasing with increasing distance from the SiC/Si interface as the lattice mismatch stress is relaxed. This observation was corroborated by a monotonic decrease in HRXRD peak width (FWHM) from 780 arcsecs (1.5 μm thick epilayer) to 350 arcsecs (10 μm thick epilayer). Significant further reduction in x-ray FWHM is possible because the minimum FWHM detected is greater than the theoretical FWHM for SiC (about 12 arcsecs). Raman spectroscopy also indicates that the residual biaxial in-plane strain decreases with increasing epilayer thickness initially, but becomes essentially constant between 6 and 10 μm. Structural defect density shows the most significant reduction in the first 2 μm of growth. Phosphorus implantation was used to generate n+/p junctions for the measurement of the critical electric field in 3C-SiC. Based on current-voltage analyses, the critical electric field in p-type 3C-SiC with a doping of 2x1017 cm-3 is 1.3x106 V/cm.

Characterization of Chemically Vapor Deposited GaN on Sic on a Simox Substrate

1997 ◽  
Vol 3 (S2) ◽  
pp. 487-488
Author(s):  
W.L. Zhou ◽  
P. Pirouz
Keyword(s):  
Lattice Mismatch ◽  
Defect Density ◽  
Silicon Layer ◽  
Large Defect ◽  
Cross Sectional ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Transmission Electron ◽  
Potential Applications ◽  
Gan Film

GaN has been intensively studied because of its potential applications for the fabrication of blue- or ultraviolet-light emitting devices. Sapphire (α-Al2O3) is generally used as the substrate for growth of GaN film. However, the large lattice mismatch between GaN and Al2O3is a possible cause of the large defect density in the GaN films. Consequently, alternative substrates are being studied with the aim of growing films of lesser defect densities and improved opto-electronic properties. In this paper, we report a transmission electron microscopy (TEM) study of a GaN film grown on cubic SiC which has been obtained by carbonization of the top silicon layer of a SIMOX substrate, i.e. the system GaN/SiC/Si/SiO2/Si.Cross-sectional TEM specimens were prepared by the conventional sandwich technique with the foil surface normal to the Si[l10] direction. The composite sample was ground and dimpled to a thickness of ∼ 10μm, and subsequently ion thinned to electron transparency.

AlGaN/GaN Based Heterostructures for MEMS and NEMS Applications

2010 ◽  
Vol 159 ◽  
pp. 27-38
Author(s):  
Volker Cimalla ◽  
C. C. Röhlig ◽  
V. Lebedev ◽  
Oliver Ambacher ◽  
Katja Tonisch ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Longitudinal Vibration ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Vibration Modes ◽  
Wide Band Gap ◽  
Group Iii ◽  
Wide Band Gap Semiconductors ◽  
Dimensional Electron Gas ◽  
Group Iii Nitride

With the increasing requirements for microelectromechanical systems (MEMS) regarding stability, miniaturization and integration, novel materials such as wide band gap semiconductors are receiving more attention. The outstanding properties of group III-nitrides offer many more possibilities for the implementation of new functionalities and a variety of technologies are available to realize group III-nitride based MEMS. In this work we demonstrate the application of these techniques for the fabrication of full-nitride MEMS. It includes a novel actuation and sensing principle based on the piezoelectric effect and employing a two-dimensional electron gas confined in AlGaN/GaN heterostructures as integrated back electrode. Furthermore, the actuation of flexural and longitudinal vibration modes in resonator bridges are demonstrated as well as their sensing properties.

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