scholarly journals Diamond Heteroepitaxial Lateral Overgrowth

2015 ◽  
Vol 1734 ◽  
Author(s):  
Y-H Tang ◽  
B. Bi ◽  
B. Golding
Keyword(s):  
Internal Stress ◽  
Diamond Films ◽  
Diamond Surface ◽  
Threading Dislocation ◽  
Thermally Induced ◽  
Structural Improvement ◽  
Lateral Overgrowth ◽  
Induced Stress ◽  
Initial Stage ◽  
Threading Dislocation Density

ABSTRACTA method of diamond heteroepitaxial lateral overgrowth is demonstrated which utilizes a photolithographic metal mask to pattern a thin (001) epitaxial diamond surface. Significant structural improvement was found, with a threading dislocation density reduced by two orders of magnitude at the top surface of a thick overgrown diamond layer. In the initial stage of overgrowth, a reduction of diamond Raman linewidth in the overgrown area was also realized. Thermally-induced stress and internal stress were determined by Raman spectroscopy of adhering and delaminated diamond films. The internal stress is found to decrease as sample thickness increases.

Details of the improvement of crystalline quality of a-plane GaN using one-step lateral growth

2006 ◽  
Vol 955 ◽  
Author(s):  
Daisuke Iida ◽  
Tetsuya Nagai ◽  
Takeshi Kawashima ◽  
Aya Miura ◽  
Yoshizane Okadome ◽  
...  
Keyword(s):  
Defect Density ◽  
Light Output ◽  
Epitaxial Lateral Overgrowth ◽  
Root Mean Square Roughness ◽  
Threading Dislocation ◽  
Light Emitting ◽  
Lateral Overgrowth ◽  
Green Led ◽  
Threading Dislocation Density ◽  
One Step

ABSTRACTLow defect density a-plane GaN films were successfully grown by sidewall epitaxial lateral overgrowth (SELO) technique. Control of V/III ratio during the growth of GaN by metalorganic vapor phase epitaxy (MOVPE) was found to be very important to achieve a complete overgrowth on the SiO2 mask regions and atomically flat surface. The threading dislocation and stacking fault densities in the overgrown regions were lower than 106 cm−2 and 103 cm−1, respectively. The root mean square roughness was 0.09 nm. We also fabricated and characterized a-plane-GaN-based-light-emitting diodes (LEDs) using SELO technique. The light output power of the blue-green LED steeply increased with the decrease of threading dislocation density from 1010 cm−2 to 108 cm−2 and tended to saturate at lower dislocation densities.

Deep centers in GaN layers grown on epitaxial lateral overgrowth templates by metalorganic chemical vapor deposition

2006 ◽  
Vol 955 ◽  
Author(s):  
Serguei A Chevtchenko ◽  
J. Xie ◽  
Y. Fu ◽  
X. Ni ◽  
H. Morkoç
Keyword(s):  
Deep Level ◽  
Reference Sample ◽  
Chemical Vapor ◽  
Dislocation Core ◽  
Epitaxial Lateral Overgrowth ◽  
Threading Dislocation ◽  
Lateral Overgrowth ◽  
Threading Dislocation Density ◽  
Line Defects ◽  
Transient Spectroscopy

ABSTRACTThe dependence of traps and their concentration in GaN on the quality of templates, on which the layers are grown, has been studied by deep-level transient spectroscopy (DLTS). Thin GaN layers studied were grown on GaN templates employing conventional epitaxial lateral overgrowth (ELO) and nano-ELO with SiNx nanonetwork. The concentrations of traps found in these layers were compared with a reference sample grown on a standard GaN template not utilizing ELO. Two traps A (0.55 eV – 0.58 eV) and B (0.20 eV – 0.23 eV) were detected in the temperature range from 80 K to 400 K. A reduction of traps in layers grown on the ELO and nano-ELO templates was noted. We attribute this reduction to the reduction of threading dislocation density and as a result reduced capture of point defects and complexes as part of dislocation core structure and/or reduced formation of defects and complexes in the vicinity of line defects where the formation can be energetically favorable.

Electron microscopy of GaAs grown on Si- and Ge-based substrates

1991 ◽  
Vol 49 ◽  
pp. 854-855
Author(s):  
D.P. Malta ◽  
J.B. Posthill ◽  
M.L. Timmons ◽  
P.R. Sharps ◽  
R. Venkatasubramanian ◽  
...  
Keyword(s):  
Critical Thickness ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Antiphase Domain ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Thermally Induced ◽  
Induced Stress ◽  
Dislocation Reduction ◽  
Domain Boundaries

A GaAs-on-Si technology is desirable to take advantage of the mobility and direct bandgap of GaAs in combination with the crystalline quality, low cost and established technology of Si. Differences in lattice constant (4.1%), thermal expansion coefficient (a factor of ~ 3), and bonding polarity between the two materials can lead to problems such as: threading dislocation formation, thermally induced stress and delamination, and antiphase domain boundaries (APBs), respectively. The lattice mismatch is responsible for the formation of (necessary) misfit dislocations which can concurrently create threading dislocations with typical densities in the range of 106 - 108cm-2. This density of electrically active defects in a device region is highly undesirable.A proposed scheme for lattice mismatch accommodation and potential threading dislocation reduction has previously been reported in which each layer of a SixGe1-x multilayer structure (MLS) is grown beyond the critical thickness with a progressively higher Ge composition than the previous layer.

scholarly journals Reduction of threading dislocation density in top-down fabricated GaN nanocolumns via their lateral overgrowth by MOCVD

2020 ◽  
Vol 127 (2) ◽  
pp. 025306 ◽  
Author(s):  
Vitaly Z. Zubialevich ◽  
Mathew McLaren ◽  
Pietro Pampili ◽  
John Shen ◽  
Miryam Arredondo-Arechavala ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Threading Dislocation ◽  
Top Down ◽  
Lateral Overgrowth ◽  
Threading Dislocation Density

High-Irradiance Degradation Studies of Metamorphic 1eV GaInAs Solar Cells

2012 ◽  
Vol 1432 ◽  
Author(s):  
Ryan M. France ◽  
Myles A. Steiner
Keyword(s):  
Solar Cells ◽  
Active Region ◽  
Dislocation Density ◽  
Dark Current ◽  
Degradation Mechanism ◽  
Control Cell ◽  
High Irradiance ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Degradation Studies

ABSTRACTInitial tests are performed regarding the degradation of lattice-mismatched GaInAs solar cells. 1eV metamorphic GaInAs solar cells with 1-2×106 cm-2 threading dislocation density in the active region are irradiated with an 808 nm laser for 2 weeks time under a variety of temperature and illumination conditions. All devices show a small degradation in Voc that is logarithmic with time. The absolute loss in performance after 2 weeks illuminated at 1300 suns equivalent and 125°C is 7 mV Voc and 0.2% efficiency, showing these devices to be relatively stable. The dark current increases with time and is analyzed with a two-diode model. A GaAs control cell degrades at the same rate, suggesting that the observed degradation mechanism is not related to the additional dislocations in the GaInAs devices.

scholarly journals Effect of Nitrogen on the Growth of (100)-, (110)-, and (111)-Oriented Diamond Films

2020 ◽  
Vol 11 (1) ◽  
pp. 126
Author(s):  
Jen-Chuan Tung ◽  
Tsung-Che Li ◽  
Yen-Jui Teseng ◽  
Po-Liang Liu
Keyword(s):  
Growth Mechanism ◽  
Density Functional ◽  
Film Growth ◽  
Hydrogen Abstraction ◽  
Diamond Films ◽  
Activation Energies ◽  
Diamond Surface ◽  
Nitrogen Doped ◽  
Nitrogen Substitution ◽  
Diamond Film Growth

The aim of this research is the study of hydrogen abstraction reactions and methyl adsorption reactions on the surfaces of (100), (110), and (111) oriented nitrogen-doped diamond through first-principles density-functional calculations. The three steps of the growth mechanism for diamond thin films are hydrogen abstraction from the diamond surface, methyl adsorption on the diamond surface, and hydrogen abstraction from the methylated diamond surface. The activation energies for hydrogen abstraction from the surface of nitrogen-undoped and nitrogen-doped diamond (111) films were −0.64 and −2.95 eV, respectively. The results revealed that nitrogen substitution was beneficial for hydrogen abstraction and the subsequent adsorption of methyl molecules on the diamond (111) surface. The adsorption energy for methyl molecules on the diamond surface was generated during the growth of (100)-, (110)-, and (111)-oriented diamond films. Compared with nitrogen-doped diamond (100) films, adsorption energies for methyl molecule adsorption were by 0.14 and 0.69 eV higher for diamond (111) and (110) films, respectively. Moreover, compared with methylated diamond (100), the activation energies for hydrogen abstraction were by 0.36 and 1.25 eV higher from the surfaces of diamond (111) and (110), respectively. Growth mechanism simulations confirmed that nitrogen-doped diamond (100) films were preferred, which was in agreement with the experimental and theoretical observations of diamond film growth.

Relationship between misfit-dislocation formation and initial threading-dislocation density in GaInN/GaN heterostructures

2015 ◽  
Vol 54 (11) ◽  
pp. 115501 ◽  
Author(s):  
Motoaki Iwaya ◽  
Taiji Yamamoto ◽  
Daisuke Iida ◽  
Yasunari Kondo ◽  
Mihoko Sowa ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Misfit Dislocation ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Dislocation Formation

Kinetic Monte Carlo Simulation of Diamond Film Growth with the Inclusion of Surface Migration

1998 ◽  
Vol 527 ◽  
Author(s):  
Armando Netto ◽  
Michael Frenklach
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Film Growth ◽  
Kinetic Monte Carlo ◽  
Diamond Films ◽  
State Theory ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Gaseous Species ◽  
Surface Migration

ABSTRACTDiamond films are of interest in many practical applications but the technology of producing high-quality, low-cost diamond is still lacking. To reach this goal, it is necessary to understand the mechanism underlying diamond deposition. Most reaction models advanced thus far do not consider surface diffusion, but recent theoretical results, founded on quantum-mechanical calculations and localized kinetic analysis, highlight the critical role that surface migration may play in growth of diamond films. In this paper we report a three-dimensional time-dependent Monte Carlo simulations of diamond growth which consider adsorption, desorption, lattice incorporation, and surface migration. The reaction mechanism includes seven gas-surface, four surface migration, and two surface-only reaction steps. The reaction probabilities are founded on the results of quantum-chemical and transition-state-theory calculations. The kinetic Monte Carlo simulations show that, starting with an ideal {100}-(2×1) reconstructed diamond surface, the model is able to produce a continuous film growth. The smoothness of the growing film and the developing morphology are shown to be influenced by rate parameter values and by deposition conditions such as temperature and gaseous species concentrations.

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