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.

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.

Mechanism for the Reduction of Threading Dislocation Densities in Si0.82Ge0.18 Films on Silicon on Insulator Substrates

2001 ◽  
Vol 673 ◽  
Author(s):  
E.M. Rehder ◽  
T.S. Kuan ◽  
T.F. Kuech
Keyword(s):  
Dislocation Density ◽  
Chemical Vapor ◽  
Dislocation Core ◽  
Extensive Study ◽  
Silicon On Insulator ◽  
Dislocation Dynamics ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Threading Dislocation Density ◽  
Soi Substrates

ABSTRACTWe have made an extensive study of Si0.82Ge0.18 film relaxation on silicon on insulator (SOI) substrates having a top Si layer 40, 70, 330nm, and 10[.proportional]m thick. SiGe films were deposited with a thickness up to 1.2[.proportional]m in an ultrahigh vacuum chemical vapor deposition system at 630°C. Following growth, films were characterized by X-ray diffraction and a dislocation revealing etch. The same level of relaxation is reached for each thickness of SiGe film independent of the substrate structure. Accompanying the film relaxation is the development of a tetragonal tensile strain in the thin Si layer of the SOI substrates. This strain reached 0.22% for the 1.2[.proportional]m film on the 40nm SOI and decreases with SOI thickness. The Si thickness of the SOI substrate also effected the threading dislocation density. For 85% relaxed films the density fell from 7×106 pits/cm2 on bulk Si to 103pits/cm2 for the 40, 70, and 330nm SOI substrates. The buried amorphous layer of the SOI substrate alters the dislocation dynamics by allowing dislocation core spreading or dislocation dissociation. The reduced strain field of these dislocations reduces dislocation interactions and the pinning that results. Without the dislocation pinning, the misfit dislocations can extend longer distances yielding a greatly reduced threading dislocation density.

Electronic Properties of Grain Boundaries in GaAs: A Study of Oriented Bicrystals Prepared by Epitaxial Lateral Overgrowth

1982 ◽  
Vol 14 ◽  
Author(s):  
Jack P. Salerno ◽  
R. W. Mcclelland ◽  
J. G. Mavroides ◽  
John C. C. Fan ◽  
A. F. Witt
Keyword(s):  
Grain Boundary ◽  
Electronic Properties ◽  
Deep Level ◽  
Depletion Region ◽  
Epitaxial Lateral Overgrowth ◽  
Lateral Overgrowth ◽  
Boundary States ◽  
Tilt Boundaries ◽  
Region Model ◽  
Transient Spectroscopy

ABSTRACTThe electronic properties of tilt boundaries with misorientation angles ranging from 0 to 30° in n-type GaAs bicrystal layers have been investigated. The current-voltage and capacitance-voltage characteristics are consistent with a double-depletion-region model. The height of the grain boundary potential barrier remains constant while the density of grain boundary states varies with misorientation angle. Deep level transient spectroscopy has revealed the presence of two bands of grain boundary states at approximately 0.65 and 0.9 eV below the conduction band. These states are attributed to bond reconstruction at the grain boundary.

Correlation Between Defect Density and Process Variables In Step-Graded, Relaxed Si0.7Ge0.3 Grown on Si by Rtcvd

1993 ◽  
Vol 303 ◽  
Author(s):  
G. Patrick Watson ◽  
Eugene A. Fitzgerald ◽  
Bahram Jalali ◽  
Ya-Hong Xie ◽  
Bonnie Weir ◽  
...  
Keyword(s):  
Defect Density ◽  
Chemical Vapor ◽  
Dark Spot ◽  
Threading Dislocation ◽  
Dark Line ◽  
Si Substrates ◽  
Transmission Electron ◽  
Threading Dislocation Density ◽  
Line Defects ◽  
Threading Defects

ABSTRACTThe effect of the average grading rate and of the number of incremental Ge alloy steps on the threading dislocation density has been studied in 30% Ge relaxed films formed by rapid thermal chemical vapor deposition (RTCVD) on Si substrates. Electron beam induced current (EBIC) images and transmission electron microscopy (TEM) show that threading defects fall in two categories: individual threading dislocations (dark spot defects), and organized clusters of these threads (pile-ups, or dark line defects). The overall surface defect density must include both categories to properly characterize the material. The lowest defect density, 4 × 105cm−2, was found in specimens grown at an average grading rate of 10% Ge per pm thickness.

scholarly journals Defect reduction in (11-20) a-plane GaN by two-step epitaxial lateral overgrowth

2006 ◽  
Vol 955 ◽  
Author(s):  
X. Ni ◽  
Ü. Özgür ◽  
Y. Fu ◽  
N. Biyikli ◽  
H. Morkoç ◽  
...  
Keyword(s):  
Near Field ◽  
Chemical Vapor ◽  
Epitaxial Lateral Overgrowth ◽  
Threading Dislocation ◽  
Wing Area ◽  
Defect Reduction ◽  
Threading Dislocation Density ◽  
Growth Method ◽  
Scanning Optical Microscopy ◽  
Window Area

ABSTRACTWe report a two-step growth method to obtain uniformly coalesced epitaxial lateral overgrown a-plane GaN by metalorganic chemical vapor deposition (MOCVD). By obtaining a large wing height to width aspect ratio in the first step followed by enhanced lateral growth in the second step via controlling the growth temperature, we reduced the tilt angle between the advancing Ga-polar and N-polar wings for improved properties. Transmission electron microscopy (TEM) showed that the threading dislocation density in the wing area was 1.0×108cm−2, more than two orders of magnitude lower than that in the window area (4.2×1010cm−2). However, a high density of basal stacking faults, 1.2×104cm−1, was still observed in the wing area. Near field scanning optical microscopy (NSOM) at room temperature revealed that the luminescence was mainly from the wing regions with very little contribution from the windows and meeting fronts. These observations suggest that due to significant reduction of threading dislocations radiative recombination is enhanced in the wings.

Electron Irradiation Induced Trap In N-Type Gan

1997 ◽  
Vol 482 ◽  
Author(s):  
Z-Q. Fang ◽  
J. W. Hemsky ◽  
D. C. Look ◽  
M. P. Mack ◽  
R. J. Molnar ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Chemical Vapor ◽  
Hydride Vapor Phase Epitaxy ◽  
Organic Chemical ◽  
Electric Field Effects ◽  
Metal Organic ◽  
Transient Spectroscopy ◽  
Organic Chemical Vapor Deposition

AbstractA 1-MeV-electron-irradiation (EI) induced trap at Ec-0.18 eV is found in n-type GaN by deep level transient spectroscopy (DLTS) measurements on Schottky barrier diodes, fabricated on both metal-organic-chemical-vapor-deposition and hydride-vapor-phase-epitaxy material grown on sapphire. The 300-K carrier concentrations of the two materials are 2.3 × 1016 cm−3 and 1.3 × 1017 cm−3, respectively. Up to an irradiation dose of 1 × 1015 cm−2, the electron concentrations and pre-existing traps in the GaN layers are not significantly affected, while the EI-induced trap is produced at a rate of at least 0.2 cm−1. The DLTS peaks in the two materials are shifted slightly, possibly due to electric-field effects. Comparison with theory suggests that the defect is most likely associated with the N vacancy or Ga interstitial.

Traps in Si-doped AlxGa1-xN Grown by Molecular Beam Epitaxy on Sapphire Characterized by Deep Level Transient Spectroscopy

2006 ◽  
Vol 955 ◽  
Author(s):  
Mo Ahoujja ◽  
S Elhamri ◽  
M Hogsed ◽  
Y. K. Yeo ◽  
R. L. Hengehold
Keyword(s):  
Molecular Beam Epitaxy ◽  
Deep Level Transient Spectroscopy ◽  
Molecular Beam ◽  
Deep Level ◽  
Unknown Origin ◽  
Shallow Donor ◽  
Related Point ◽  
Line Defects ◽  
Si Doped ◽  
Transient Spectroscopy

ABSTRACTDeep levels in Si doped AlxGa1−xN samples, with Al mole fraction in the range of x = 0 to 0.30, grown by radio-frequency plasma activated molecular beam epitaxy on sapphire substrates were characterized by deep level transient spectroscopy (DLTS). DLTS measurements show two significant electron traps, P1 and P2, in AlGaN at all aluminum mole fractions. The electron trap, P2, appears to be a superposition of traps A and B , both of which are observed in GaN grown by various growth techniques and are thought to be related to VGa-shallow donor complexes. Trap P1 is related to line defects and N-related point defects. Both of these traps are distributed throughout the bulk of the epitaxial layer. An additional trap P0 which was observed in Al0.20Ga0.80N and Al0.30Ga0.70N is of unknown origin, but like P1 and P2, it exhibits dislocation-related capture kinetics. The activation energy measured from the conduction band of the defects is found to increase with Al mole content, a behavior consistent with other III-V semiconductors.

Properties of the EL2 Level in Organometallic Ga1−xAlxAs

1987 ◽  
Vol 104 ◽  
Author(s):  
A. Ben Cherifa ◽  
R. Azoulay ◽  
G. Guillot
Keyword(s):  
Vapor Deposition ◽  
Deep Level Transient Spectroscopy ◽  
Metalorganic Chemical Vapor Deposition ◽  
Deep Level ◽  
Chemical Vapor ◽  
Electron Trap ◽  
Quenching Effect ◽  
Deep Electron Trap ◽  
Transient Spectroscopy ◽  
First Time

ABSTRACTWe have studied by means of deep level transient spectroscopy and photocapacitance measurements deep electron traps in undoped Ga1−xAlxAs of n-type grown by metalorganic chemical vapor deposition with 0≤x≤ 0.3. A dominant deep electron trap is detected in the series of alloys. Its activation energy is found at EC-0.8 eV in GaAs and it increases with x. Its concentration is found nearly independent of x. For the first time we observed for this level in the Ga1−xAlxAs alloys, the photocapacitance quenching effect typical for the EL2 defect in GaAs thus confirming clearly that EL2 is also created in MOCVD Ga1−xAlxAs.

Reduction of Threading Dislocation Density in AlGaN by Indium Incorporation

2003 ◽  
Vol 798 ◽  
Author(s):  
H. Kang ◽  
Z. C. Feng ◽  
I. Ferguson ◽  
S. P. Guo ◽  
M. Pophristic
Keyword(s):  
Dislocation Density ◽  
Structural Properties ◽  
Coherence Length ◽  
Chemical Vapor ◽  
Columnar Structure ◽  
Organic Chemical ◽  
Threading Dislocation ◽  
Reciprocal Space Mapping ◽  
Threading Dislocation Density ◽  
Metal Organic

ABSTRACTThe addition of indium, even to small concentrations, to AlGaN has resulted in improved optical and doping properties for these materials. This paper is the first report of improved structural properties for indium containing AlGaN layers. A systematic series of the AlGaN layers with nominal concentration of 20% aluminum were grown by metal-organic chemical vapor deposition with traces amounts of indium incorporated into the layers (up to 0.15% indium). X-ray diffraction analysis of the layers was completed using Williamson Hall plots and reciprocal space mapping to investigate any change in the columnar structure of the initial AlGaN layers. It was found that the threading dislocation densities and lateral coherence length showed a systematic variation with indium incorporation. The threading dislocation density is lowered as indium composition increased with a corresponding increase in lateral coherence length. This indicates that even the incorporation of trace amounts of indium improves the structural properties of these epilayers.

Sign in / Sign up

Export Citation Format

Share Document