A Study of the Decomposition of GaN during Annealing over a Wide Range of Temperatures

2002 ◽  
Vol 743 ◽  
Author(s):  
M. A. Rana ◽  
H. W. Choi ◽  
M. B. H. Breese ◽  
T. Osipowicz ◽  
S. J. Chua ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Depth Resolution ◽  
Surface Region ◽  
Organic Chemical ◽  
Near Surface ◽  
Wide Range ◽  
Metal Organic ◽  
Amorphous Surface ◽  
Nitride Layers

ABSTRACTAnnealing experiments were carried out on gallium nitride layers, which were grown on sapphire through Metal Organic Chemical Vapor Deposition (MOCVD). Rutherford Backscattering Spectrometry (RBS) was performed on as-grown and annealed GaN samples using a 2 MeV proton beam to study the stoichiometric changes in the near-surface region (750 nm) with depth resolution better than 50 nm. No decomposition was measured for temperatures o up to 800 °C. Decomposition in the near-surface region increased rapidly with a further increase o of temperature, resulting in a near-amorphous surface-region for annealing at 1100 °C. The depth profiles of nitrogen and incorporated oxygen in the decomposed GaN are extracted from the nanoscale RBS data for different annealing temperatures. The surface roughness of the GaN layers observed by atomic force microscopy (AFM) is consistent with RBS decomposition measurements. We describe the range of annealing conditions under which negligible decomposition of GaN is observed, which is important in assessing optimal thermal processing conditions of GaN for both conventional and nanoscale optoelectronic devices.

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

DEPTH-DEPENDENT TETRAGONAL DISTORTION STUDY OF AlGaN EPILAYER THIN FILM USING RBS AND CHANNELING TECHNIQUE

2012 ◽  
Vol 26 (14) ◽  
pp. 1250086 ◽  
Author(s):  
G. HUSNAIN ◽  
ISHAQ AHMAD ◽  
SHU-DE YAO ◽  
H. M. RAFIQUE ◽  
AKRAJAS ALI UMAR ◽  
...  
Keyword(s):  
Compressive Strain ◽  
Chemical Vapor ◽  
Wide Band ◽  
Tetragonal Distortion ◽  
Organic Chemical ◽  
Algan Layer ◽  
Wide Band Gap ◽  
Near Surface ◽  
Good Crystalline Quality ◽  
Metal Organic

An epilayer of wide-band gap Al x Ga 1-x N was grown on sapphire by metal organic chemical vapor deposition (MOCVD) method with a GaN buffer layer of thickness slightly greater than 1 μm. Average composition of Al in the AlGaN layer is determined by Rutherford backscattering spectroscopy (RBS). Simulation of the random spectra reveals that the AlGaN layer has a composition of Al 0.05 Ga 0.95 N and a thickness of 200 nm. Low ratio of channeling and random spectra yields suggests good crystalline quality of ternary AlGaN epilayer. Tetragonal distortion (eT) caused by elastic strain in AlGaN is measured from channeling angular scans taken around an off-normal [Formula: see text] axis in the [Formula: see text] plane of the AlGaN layer. The resulting AlGaN is identified to be showing compressive strain at the interfacial layer and the magnitude of the stress reduces towards the near-surface layer. It can be expected from the results that a 550 nm thick, epitaxially grown, AlGaN layer on sapphire can be relaxed completely (eT = 0).

A Nucleation Study of GaN Multifunctional Nanostructures

2004 ◽  
Vol 831 ◽  
Author(s):  
Gupta Shalini ◽  
Kang Hun ◽  
Strassburg Martin ◽  
Asghar Ali ◽  
Senawiratne Jayantha ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Organic Chemical ◽  
Mocvd Growth ◽  
Aspect Ratios ◽  
Nucleation Sites ◽  
Wide Range ◽  
Metal Organic ◽  
Multifunctional Nanostructures

ABSTRACTThis paper reports the Metal Organic Chemical Vapor Deposition (MOCVD) growth of GaN nanostructures. The use of MOCVD allows the direct integration of these nanostructures into pre-existing device technology. The formation of GaN nanostructures grown on AlN epitaxial layers were studied as a function of growth temperature, growth rate, V-III ratio and the amount of deposited material. A wide range of temperatures from 800 °C to 1100 °C and V-III ratios from 30 to 3500 were applied to determine the optimal growth conditions for nucleation studies in a modified production reactor. Small GaN nanostructures with lateral dimensions below 50 nm and low aspect ratios were obtained using relatively low temperatures of 815 °C and extreme metal-rich growth conditions. Island densities up to 1010 cm−2 were achieved using silane as an anti-surfactant to increase the available nucleation sites. Manganese has been incorporated into these nanostructures to enhance the multifunctional ferromagnetic properties of GaMnN.

Epitaxial thin films of PbTiO3/SnO2 heterostructures on sapphire

1994 ◽  
Vol 9 (12) ◽  
pp. 3108-3112 ◽  
Author(s):  
H.L.M. Chang ◽  
H. Zhang ◽  
Z. Shen ◽  
Q. Wang
Keyword(s):  
Material Selection ◽  
Single Layer ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Epitaxial Thin Films ◽  
Ferroelectric Films ◽  
Epitaxial Relationship ◽  
Transmission Electron ◽  
Wide Range ◽  
Metal Organic

Epitaxial films of single-layer SnO2 and PbTiO3/SnO2 heterostructures were obtained on (0001) sapphire (α-Al2O3) substrates by metal-organic chemical vapor deposition. X-ray diffraction and transmission electron microscopy were used to characterize the structural properties of these films. The epitaxial relationship for the heterostructure PbTiO3/SnO2/sapphire was found to be (111) [011]PbTiO3 ‖ (100) [001]SnO2 ‖ (0001) [1100]α-Al2O3. The fact that epitaxial ferroelectric films were obtainable in such a structurally highly heterogeneous system suggests that a wide range of material selection is possible in exploring the kind of applications that need to utilize epitaxial ferroelectric films in a multilayered heterostructure.

Study of Depth-Dependent Tetragonal Distortion of GaN Epilayer with Tri-Layer AlGaN Interlayer Growth on Si(111)

2011 ◽  
Vol 413 ◽  
pp. 11-17 ◽  
Author(s):  
Bin Feng Ding ◽  
Yong Quan Chai
Keyword(s):  
Chemical Vapor ◽  
Crystal Quality ◽  
Tetragonal Distortion ◽  
Organic Chemical ◽  
X Ray Diffraction ◽  
Near Surface ◽  
X Ray ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

A GaN epilayer with tri-layer AlGaN interlayer grown on Si (111) by metal-organic chemical vapor deposition (MOCVD) method was discussed by synchrotron radiation x-ray diffraction (SRXRD) and Rutherford backscattering (RBS)/C. The crystal quality of the epilayer is very good with a χmin=2.1%. According to the results of the θ-2θ scan of GaN(0002) and GaN(1122), the epilayer elastic strains in perpendicular and parallel directions were calculated respectively to be-0.019% and 0.063%. By the angular scan using RBS/C around a symmetric [0001] axis and an asymmetric [1213] axis in the (1010) plane of the GaN layer, the tetragonal distortion (eT ) were determined to be 0.09%. This result coincides with that from SRXRD perfectly. The strain decreases gradually towards the near-surface layer, which will avoid the film cracks efficiently and improve the crystal quality of the GaN epilayer remarkably.

Thermal Stability of Pt, Pd, and Ni on GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
K. J. Duxstad ◽  
E. E. Haller ◽  
K.M. Yu ◽  
M. T. Hirsch ◽  
W. R. Imler ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Structural Changes ◽  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Contact Structures ◽  
Organic Chemical ◽  
X Ray Diffraction ◽  
Surface Behavior ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

ABSTRACTThe development of reliable Ohmic and Schottky contacts on GaN will require an understanding of the thermal stability and metallurgy of metal-GaN contact structures. We investigated the behavior of Pt, Pd, and Ni on GaN as a function of annealing temperature. Rutherford backscattering spectrometry, x-ray diffraction, and scanning electron microscopy were used to characterize the interface and surface behavior. 800Å thin metal films were deposited by sputtering on 2μm GaN films grown by metal organic chemical vapor deposition on sapphire substrates. No reactions occur in the Pt, Pd, and Ni systems with annealing up to 800°C. The Pt film begins to form submicron spheres and islands after annealing above 600°C. The Pd and Ni films begin to island with annealing above 700°C. Below these temperatures no structural changes were observed.

In-Situ Monitoring Of Mocvd Grown Inall_ As/Gaas Epitaxial Layers By Two Laser Beams Reflectometry

1995 ◽  
Vol 406 ◽  
Author(s):  
Jong-Hyeob Baek ◽  
Bun Lee ◽  
Sung Woo Choi ◽  
Jin Hong Lee ◽  
El-Hang Lee
Keyword(s):  
Chemical Vapor ◽  
Index Of Refraction ◽  
In Situ Monitoring ◽  
Laser Beams ◽  
Organic Chemical ◽  
Epitaxial Layers ◽  
Photovoltaic Detectors ◽  
Wide Range ◽  
Metal Organic

AbstractWe report application of in-situ laser reflectometry in monitoring InAl1−xAs (0 ≤ x ≤1) epitaxial layers grown on a GaAs substrate by low pressure metal-organic chemical vapor deposition. Two different lasers were used simultaneously: One was a He-Ne laser operating at 0.6328 μm and the other was a diode laser operating at 1.53 μm. The two laser beams were incident on the growing layer at an angle of 71° from the surface normal, and the reflected beams were detected by Si and Ge photovoltaic detectors, respectively. Since the epitaxial layer of InxAl1−xAs (0 ≤ x ≤1) has a wide range of index of refraction, the reflected signals showed a variety of patterns. The optical constants of the InxAl1−xAs epitaxial layers were obtained for the entire range of composition.

Single molecular precursor metal-organic chemical vapor deposition of MgAl2O4 thin films

1994 ◽  
Vol 9 (6) ◽  
pp. 1333-1336 ◽  
Author(s):  
Jiming Zhang ◽  
Gregory T. Stauf ◽  
Robin Gardiner ◽  
Peter Van Buskirk ◽  
John Steinbeck
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Liquid Solution ◽  
Organic Chemical ◽  
Starting Compound ◽  
Wide Range ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

MgAl2O4 films have been grown epitaxially on both Si(100) and MgO(100) by a novel single source metal-organic chemical vapor deposition (MOCVD) process. A single molecular source reagent [magnesium dialuminum isopropoxide, MgAl2(OC3H7)8] having the desired Mg: Al ratio was dissolved in a liquid solution and flash-vaporized into the reactor. Both thermal and plasma-enhanced MOCVD were used to grow epitaxial MgAl2O4 thin films. The Mg: Al ratio in the deposited films was the same as that of the starting compound (Mg: Al = 1:2) over a wide range of deposition conditions. The deposition temperature required for the formation of crystalline spinel was found to be significantly reduced and crystallinity was much improved on Si by using a remote plasma-enhanced MOCVD process. The epitaxial nature of the MgAl2O4 films was established by x-ray pole figure analysis.

Study of the growth of TiO2 on A12O3 by pulsed-laser ablation

1994 ◽  
Vol 52 ◽  
pp. 642-643
Author(s):  
M. W. Bench ◽  
C.B. Carter
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Pulsed Laser ◽  
Chemical Vapor ◽  
Pulsed Laser Ablation ◽  
Organic Chemical ◽  
Wide Range ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition ◽  
Deposition Techniques

There has been an increasing interest in recent years in the growth of epitactic oxide thin films for use in a variety of technological applications, including optical and electronic devices. A number of fundamental aspects of the growth of TiO2 films on alumina substrates by metal-organic chemical vapor deposition have been reported by Chang et al. For the case of MgO, Hesse et al. demonstrated the epitactic growth by pulsed-laser deposition of YBa2Cu3O7-x on (001) MgO passivated by a layer of the inverse spinel Mg2TiO4. The Mg2TiO4 layer was formed directly by a vapor-phase solid-state reaction during the deposition by e-beam evaporation of TiO2 onto heated MgO substrates. In other studies, TiO2 thin films have been grown using a variety of deposition techniques. For the growth of oxide materials in general, pulsed-laser ablation is a viable means of growing films, and allows materials with a wide range of stoichiometrics to be produced.

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