Nanoscale Features Grown by MBE on Nonplanar Patterned Si Substrates

1995 ◽  
Vol 380 ◽  
Author(s):  
Karl D. Hobart ◽  
Fritz J. Kub ◽  
Henry F. Gray ◽  
Mark E. Twigg ◽  
Doewon Park ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Growth Parameters ◽  
Multiple Quantum ◽  
Electron Microscopies ◽  
Si Substrates ◽  
Transmission Electron ◽  
Low Dimensional ◽  
20 Nm ◽  
Nanoscale Features ◽  
Qualitative Changes

ABSTRACTSi growth by molecular beam epitaxy on nonplanar patterned Si substrates is studied as a function of growth parameters. The substrates consist of a truncated pyramid template with {111} sides and (100) tops formed by anisotropic etching of Si(100). For growth temperatures ≤ 550°C no qualitative changes in the morphology of the template are observed. At growth temperatures between 650–700°C {113} facets begin to form on the (100) surface and reduce the lateral dimensions of the (100) facet to < 20 nm. At high temperatures (∼800°C) {113} facets remain stable and {111} facets no longer exist. The small (100) mesa formed at medium temperatures by facet reduction is exploited through the growth of Si/Si 1-xGex multiple quantum wells leading to low-dimensional structures. Observations are quantified by scanning electron and transmission electron microscopies.

High-efficiency near-UV light-emitting diodes on Si substrates with InGaN/GaN/AlGaN/GaN multiple quantum wells

2020 ◽  
Vol 8 (3) ◽  
pp. 883-888 ◽  
Author(s):  
Yuan Li ◽  
Zhiheng Xing ◽  
Yulin Zheng ◽  
Xin Tang ◽  
Wentong Xie ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Uv Light ◽  
Multiple Quantum ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Si Substrates

High quantum efficiency LEDs with InGaN/GaN/AlGaN/GaN MQWs have been demonstrated. The proposed GaN interlayer barrier can not only increase the concentration and the spatial overlap of carriers, but also improve the quality of the MQWs.

V-Defect and Dislocation Analysis in InGaN Multiple Quantum Wells on Patterned Sapphire Substrate

2018 ◽  
Vol 787 ◽  
pp. 37-41
Author(s):  
Huan You Wang ◽  
Qiao Lai Tan ◽  
Gui Jin
Keyword(s):  
Quantum Wells ◽  
Strain Relaxation ◽  
Chemical Vapor ◽  
Multiple Quantum ◽  
Cross Sectional ◽  
Patterned Sapphire Substrate ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Multi Quantum Well ◽  
Patterned Sapphire Substrates

InGaN/GaN multiquantum well (MQW) structures have been grown on cone-shaped patterned sapphire substrates (CPSS) by metalorganic chemical vapor deposition (MOCVD). From the transmission electron microscopy (TEM) results, we found that most of the threading dislocations (TDs) in the trench region of the CPSS were bent by lateral growth mode. Also the staircase-like TDs were observed near the slant region of the cone pattern, they converged at the slope of the cone patterned region by staircase-upward propagation, which seems to effectively prevent TDs from vertical propagation in the trench region. The associated dislocation runs up into the overgrown GaN layer and MQW, and some (a+c) dislocations were shown to decompose inside the multi-quantum well, giving rise to a misfit segment in the c-plane and a V-shape defect. From cross-sectional TEM, we found that all V defects are not always connected with TDs at their bottom, some V defects are generated from the stacking mismatch boundaries induced by stacking faults which are formed within the MQW due to the strain relaxation.

Multi-Wavelength Emitting InGaN/GaN Quantum Well Grown on V-Shaped GaN(1101) Microfacet

2007 ◽  
Vol 7 (11) ◽  
pp. 4053-4056 ◽  
Author(s):  
Eun-Sil Kang ◽  
Jin-Woo Ju ◽  
Jin Soo Kim ◽  
Haeng-Keun Ahn ◽  
June Key Lee ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emitting Diode ◽  
Multiple Quantum ◽  
Continuous Change ◽  
Light Emitting ◽  
Transmission Electron ◽  
Luminescence Peak ◽  
Multi Wavelength ◽  
Upward Direction ◽  
Conventional Photolithography

InGaN/GaN multiple quantum wells (MQWs) were successfully grown on the inclined GaN(1101) microfacets. Conventional photolithography and subsequent growth of GaN were employed to generate the V-shaped microfacets along 〈1120〉 direction. The well-developed microfacets observed by scanning electron microscopy and the clear transmission electron microscope interfacial images indicated that the MQW was successfully grown on the GaN microfacets. Interestingly, cathodoluminescence (CL) spectra measured on the microfacets showed a continuous change in the luminescence peak positions. The CL peaks were shifted to a longer wavelength from 420 nm to 440 nm as the probing points were changed along upward direction. This could be attributed to the non-uniform distribution of the In composition and/or the wavefunction overlapping between adjacent wells. Present works thus propose a novel route to fabricate a monolithic white light emitting diode without phosphors by growing the InGaN/GaN MQWs on (1101) facet.

“In-Situ Network” Composite Fibers of Pbzt/Nylon

1988 ◽  
Vol 134 ◽  
Author(s):  
C. Robin Hwang ◽  
Michael F. Malone ◽  
Richard J. Farris ◽  
David C. Martin ◽  
Edwin L. Thomas
Keyword(s):  
Nitrogen Adsorption ◽  
Composite Fibers ◽  
Electron Microscopies ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Before And After ◽  
The Matrix ◽  
Novel Method ◽  
20 Nm

ABSTRACTA novel method of preparing PBZT/nylon composite fibers by infiltrating nylon into pure PBZT fiber is described. The pure PBZT fiber formed a microfibrillar network structure during coagulation, which is effective in reinforcing the matrix in the “in-situ network” composite fibers (designated IC). These new composite fibers exhibit nearly indistinguishable mechanical properties as those of “molecular” composite fibers (MC) prepared from isotropic solutions before and after tension heat-treatment (E = 44 GPa, σ = 430 MPa, ε = 1.2 %, σc = 250 MPa, G = 1.75 GPa) for PBZT/nylon weight ratios equal to unity.The fine structure of pure PBZT and its composite fibers spun from isotropic solutions was characterized using techniques based on nitrogen adsorption, small-angle X-ray scattering, scanning and transmission electron microscopies. The structure of both type of composites was found to be a microfibrillar network of PBZT in a matrix of amorphous nylon. The average diameters of the PBZT microfibrils were in the range of 10 to 20 nm for the IC and 4 nm for the MC.

Ordered Structure in GalnP/AIGalnP Quantum Wells and p-Doped Multiquantum Well AIGalnp Laser Diodes

1991 ◽  
Vol 240 ◽  
Author(s):  
Toshiaki Tanaka ◽  
Hironori Yanagisawa ◽  
Shin-Ichiro Yano ◽  
Shigekazu Minagawa
Keyword(s):  
Quantum Wells ◽  
Hole Concentration ◽  
Laser Diodes ◽  
Ordered Structure ◽  
Transmission Electron ◽  
Zinc Doping ◽  
Low Threshold ◽  
Diffraction Patterns ◽  
20 Nm ◽  
Multiquantum Well

ABSTRACTZinc doping is performed on the GalnP/AIGalnP multiquantum well (MQW) structure with the aim of dissolving the ordered atomic arrangement which results in higher quantum levels and therefore shorter lasing wavelengths. It is shown that the photoluminescence (PL) peak wavelength gradually shortens with doping and decreases by 20 nm when the hole concentration reaches 1×1018 cm−3, while the PL relative intensity becomes half that of an undoped MQW layer. Therefore, a moderate level of zinc doping of around 4∼5×1017 cm−3 is desirable to shorten the PL wavelength without decreasing the crystal quality. Transmission electron nano-diffraction patterns confirm that the ordered structure in the MQW layers disappears as the hole concentration increases. On the basis of this data, uniformly p-doped and modulation p-doped MQW laser diodes are fabricated and their characteristics are compared with the undoped MQW lasers. CW operation is achieved at wavelengths of 631 to 633 nm, which is 10 nm shorter than the 643 nm in an undoped MQW laser. Comparatively low threshold currents of 73 and 88 mA are attained for uniformly p-doped and modulation p-doped MQW lasers, respectively. However, they are about 20∼30 mA higher than those of the undoped MQW lasers. This results from the large overflow of electrons from the active layer, and the fact that the differential gain becomes smaller in the 630-nm band.

Characterization of Nano-size Indium Cluster in InGaN/GaN Multiple QuantumWells with High Indium Composition

2003 ◽  
Vol 775 ◽  
Author(s):  
Hyung Koun Cho ◽  
Jeong Yong Lee
Keyword(s):  
Quantum Wells ◽  
Multiple Quantum Well ◽  
Localized States ◽  
Multiple Quantum ◽  
Emission Properties ◽  
Indium Composition ◽  
Transmission Electron ◽  
Integrated Intensity ◽  
Nano Size

AbstractWe report the effect of strain-induced indium clustering on the emission properties of InGaN/GaN multiple quantum wells grown with high indium composition by MOCVD. Nanosize indium clustering confirmed by high-resolution transmission electron microscopy results in the redshift of the emission peak and the increase of the integrated photoluminescence (PL) intensity. We found that strong carrier localization in indium clustering induces the increases of the activation energy of PL integrated intensity and the temperature independence of PL decay profiles. All these observations suggest structurally and optically that the improved emission properties in the InGaN/GaN multiple quantum well with high indium composition are associated with the localized states in the nano-size indium cluster.

InGaN/GaN Multiple Quantum Well Blue LEDs on 3C-SiC/Si Substrate

2011 ◽  
Vol 679-680 ◽  
pp. 801-803
Author(s):  
Ji Sheng Han ◽  
Sima Dimitrjiev ◽  
Li Wang ◽  
Alan Iacopi ◽  
Qu Shuang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Epitaxial Growth ◽  
Light Emission ◽  
Multiple Quantum Well ◽  
Multiple Quantum Wells ◽  
Structural Quality ◽  
Multiple Quantum ◽  
Si Substrate ◽  
Si Substrates

Gallium nitrides are primarily used for their excellent light emission properties. GaN LEDs are mostly grown on foreign substrates, essentially sapphire and SiC, but more recently, also on Si substrates. In this paper, we will demonstrate that the high structural quality of InGaN/GaN multiple quantum wells can be deposited on 3C-SiC/Si (111) substrate using MOCVD. This demonstrates that 3C-SiC/Si is a promising template for the epitaxial growth of InGaN/GaN multiple quantum wells for LEDs.

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