Thin Film Crystalline Organic Semiconductors: A New Class of Engineered Materials for Optoelectronics

1992 ◽  
Vol 247 ◽  
Author(s):  
E. I. Haskal ◽  
F. F. So ◽  
D. Y. Zang ◽  
S. R. Forrest
Keyword(s):  
Thin Films ◽  
Quantum Wells ◽  
Organic Semiconductors ◽  
Organic Thin Films ◽  
Multiple Quantum ◽  
Inorganic Semiconductors ◽  
New Class ◽  
Molecular Beam Deposition ◽  
Wide Range ◽  
Engineered Structures

ABSTRACTWe have demonstrated that a class of stable aromatic compounds based on perviene and naphthalene can be deposited in extensive single crystalline thin films using the ultrahigh vacuum process of organic molecular beam deposition (OMBD). Furthermore, highly ordered “quasi-epitaxial” structures consisting of alternating, ultra-thin (to 10A) layers of two or more crystalline organic compounds have also been grown using this novel process, thus opening the door to a wide range of artificially “engineered” structures analogous to conventional semiconductor multiple quantum wells (MQWs). Unlike the case of inorganic semiconductors, however, organic materials bonded by the flexibly van der Waals forces are free of the need to choose layer compositions from materials whose crystal structures are matched. In this paper we summarize many of the unusual growth and materials characteristics of quasi-epitaxial organic thin films grown by OMBD.

Optoelectronic and Structural Properties of Vacuum-Deposited Crystalline Organic Thin Films

1993 ◽  
Vol 328 ◽  
Author(s):  
S. R. Forrest ◽  
P. E. Burrows ◽  
E. I. Haskal ◽  
Y. Zhang
Keyword(s):  
Thin Films ◽  
Quantum Wells ◽  
Field Effect Transistors ◽  
Organic Thin Films ◽  
Potential Method ◽  
Organic Films ◽  
Light Emitting ◽  
Organic Monolayer ◽  
Molecular Beam Deposition ◽  
Monolayer Growth

ABSTRACTRecently, it has been discovered that crystalline organic thin films can be deposited in nearly single crystalline form on a variety of substrates such as glass, polymers, etc. Since then, this discovery has led to the growth of crystalline organic quantum wells, waveguides, coupler/switches, and organic/ inorganic heterojunction devices such as field effect transistors and avalanche photodiodes. Organic light emitting diodes (LEDs) which luminesce in the red, green and blue have also been demonstrated. In this paper, we will report on several recent advances in the growth of organic thin films deposited by organic molecular beam deposition. We report on modeling of organic monolayer growth based on the atom-atom potential Method. The Model provides insight into the factors which control “quasi-epitaxial growth” i.e. the ordered growth of one layer of an organic film which is incommensurate with the substrate lattice. We also observe large optical nonlinearities which are a feature of both single and Multi-layer crystalline organic films. The growth of organic, nonlinear optically active crystalline organic compounds are also discussed.

Self-Assembly Growth of Organic Thin Films and Nanostructures by Molecular Beam Deposition

2001 ◽  
pp. 34-49 ◽  
Author(s):  
Chengzhi Cai ◽  
Martin Bösch ◽  
Christian Bosshard ◽  
Bert Müller ◽  
Ye Tao ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
Molecular Beam ◽  
Organic Thin Films ◽  
Molecular Beam Deposition ◽  
Beam Deposition

Characterization and Griwth of Oicanic Multiple Qanm Well Structures

1990 ◽  
Vol 198 ◽  
Author(s):  
F.F. So ◽  
S.R. Forrest ◽  
Y.Q. Shi ◽  
W.H. Steier
Keyword(s):  
Quantum Well ◽  
Layer Thickness ◽  
Organic Semiconductors ◽  
Multiple Quantum Well ◽  
Energy Shift ◽  
Blue Shift ◽  
Multiple Quantum ◽  
Quantum Well Structures ◽  
Singlet Exciton ◽  
Molecular Beam Deposition

ABSTRACTMultiple quantum well structures consisting of alternating layers of two crystalline organic semiconductors, namely, 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) and 3,4,7,8 naphthalenetetracarboxylic dianhydride (NTCDA), have been grown by organic molecular beam deposition. The layer thickness was varied from 10 to 200 Å. Birefringence measurements indicate that there is a strong structural ordering in all PrCDA layers, although the PrCDA and NTCDA crystal structures are incommensurate. From optical absorption measurements, it is found there is a blue shift in the lowest energy PICDA singlet exciton line with decreasing layer thickness. A model based on exciton quantum confinement is proposed to explain the energy shift. We have measured the low temperature photoluminescence spectra of organic quantum well structures, and found a slight red shift in the spectra with decreasing well width. These results are also discussed.

Rapid Thermal Processing of Buried Sil−xGex Strained Layers; Photoluminescence Decay and Misfit Dislocation Generation.

1990 ◽  
Vol 198 ◽  
Author(s):  
D.C. Houghton ◽  
N.L. Rowell
Keyword(s):  
Quantum Wells ◽  
Misfit Dislocation ◽  
Thermal Processing ◽  
Internal Quantum Efficiency ◽  
Dislocation Nucleation ◽  
Multiple Quantum ◽  
Misfit Dislocations ◽  
Dislocation Generation ◽  
Strained Layers ◽  
Wide Range

ABSTRACTThe thermal constraints for device processing imposed by strain relaxation have been determined for a wide range of Si-Ge strained heterostructures. Misfit dislocation densities and glide velocities in uncapped Sil-xGex alloy layers, Sil-xGex single and multiple quantum wells have been measured using defect etching and TEM for a range of anneal temperatures (450°C-1000°C) and anneal times (5s-2000s). The decay of an intense photoluminescence peak (∼ 10% internal quantum efficiency ) from buried Si1-xGex strained layers has been correlated with the generation of misfit dislocations in adjacent Sil-xGex /Si interfaces. The misfit dislocation nucleation rate and glide velocity for all geometries and alloy compositions (0<x<0.25) were found to be thermally activated processes with activation energies of (2.5±0.2)eV and (2.3-0.65x)eV, respectively. The time-temperature regime available for thermal processing is mapped out as a function of dislocation density using a new kinetic model.

scholarly journals Photoreflectance Spectroscopy Characterization of Ge/Si0.16Ge0.84Multiple Quantum Wells on Ge Virtual Substrate

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Hung-Pin Hsu ◽  
Pong-Hong Yang ◽  
Jeng-Kuang Huang ◽  
Po-Hung Wu ◽  
Ying-Sheng Huang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Interband Transition ◽  
Multiple Quantum Well ◽  
Chemical Vapor ◽  
Detailed Comparison ◽  
Multiple Quantum ◽  
Temperature Dependent ◽  
Wide Range ◽  
Quantum Confined

We report a detailed characterization of a Ge/Si0.16Ge0.84multiple quantum well (MQW) structure on Ge-on-Si virtual substrate (VS) grown by ultrahigh vacuum chemical vapor deposition by using temperature-dependent photoreflectance (PR) in the temperature range from 10 to 300 K. The PR spectra revealed a wide range of optical transitions from the MQW region as well as transitions corresponding to the light-hole and heavy-hole splitting energies of Ge-on-Si VS. A detailed comparison of PR spectral line shape fits and theoretical calculation led to the identification of various quantum-confined interband transitions. The temperature-dependent PR spectra of Ge/Si0.16Ge0.84MQW were analyzed using Varshni and Bose-Einstein expressions. The parameters that describe the temperature variations of various quantum-confined interband transition energies were evaluated and discussed.

Electroluminescence Properties of InGaN/AlGaN/GaN Light Emitting Diodes with Quantum Wells

1998 ◽  
Vol 537 ◽  
Author(s):  
A.E. Yunovich ◽  
V.E. Kudryashov ◽  
A..N. Turkin ◽  
A.N. Kovalev ◽  
F.I. Manyakhin
Keyword(s):  
Quantum Wells ◽  
Large Scale ◽  
Light Emitting Diodes ◽  
Spectral Band ◽  
High Energy ◽  
Model Fit ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Wide Range ◽  
Tunnel Effects

AbstractElectroluminescence spectra of light-emitting diodes based on InGaN/AlGaN/GaN heterostructures with single and multiple quantum wells (QWs) are analyzed by models of radiative recombination in 2D-structures with band tails. Equations of the model fit spectra quite good in a wide range of currents. Parameters of the fit are discussed and compared for single and multiple QWs. Tunnel effects play a sufficient role in blue LEDs with single QWs at low currents; they can be neglected in LEDs with multiple QWs. A new spectral band was detected at the high energy side of the spectra of green LEDs with multiple QWs; it is attributed with large scale inhomogenities of In distribution in InGaN QWs.)

scholarly journals Post-Deposition Wetting and Instabilities in Organic Thin Films by Supersonic Molecular Beam Deposition

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Fabio Chiarella ◽  
Carmine Antonio Perroni ◽  
Federico Chianese ◽  
Mario Barra ◽  
Gabriella Maria De Luca ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Beam ◽  
Organic Thin Films ◽  
Supersonic Molecular Beam ◽  
Molecular Beam Deposition ◽  
Post Deposition ◽  
Beam Deposition

Multiple quantum well optical nonlinearities: bistability from increasing absorption and the self electro-optic device

1984 ◽  
Vol 313 (1525) ◽  
pp. 239-244 ◽  
Keyword(s):  
Quantum Wells ◽  
Optical Switching ◽  
Optical Switch ◽  
Resonant Cavity ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Optical Modulators ◽  
New Class ◽  
Electro Optic ◽  
Semiconductor Electronics

This paper briefly reviews the nonlinear optical and electro-optical properties and applications of GaAs—AlGaAs multiple quantum wells, all of which are compatible with laser diodes or semiconductor electronics or both. They show large nonlinear absorption and refraction (associated with their strong room-temperature exciton resonances) applicable to all-optical devices. They also show large electroabsorptive effects, some of which are unique to the quantum wells at any temperature, which are so strong that optical modulators can be made with micrometre dimensions. A new class of optical bistability (due to increasing absorption) is also reviewed; combination of this with the electroabsorptive effects enables a new mirrorless optical switch called a Self Electro-optic Effect Device (SEED), which sets a new standard for optical switching energies, with energy densities reduced by a factor of six by comparison to even the best resonant cavity devices.

scholarly journals Pair distribution functions of amorphous organic thin films from synchrotron X-ray scattering in transmission mode

IUCrJ ◽  
2017 ◽  
Vol 4 (5) ◽  
pp. 555-559 ◽  
Author(s):  
Chenyang Shi ◽  
Rattavut Teerakapibal ◽  
Lian Yu ◽  
Geoff G. Z. Zhang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Amorphous State ◽  
Organic Thin Films ◽  
High Energy ◽  
Transmission Mode ◽  
Organic Thin Film ◽  
Total Scattering ◽  
X Ray ◽  
Wide Range

Using high-brilliance high-energy synchrotron X-ray radiation, for the first time the total scattering of a thin organic glass film deposited on a strongly scattering inorganic substrate has been measured in transmission mode. The organic thin film was composed of the weakly scattering pharmaceutical substance indomethacin in the amorphous state. The film was 130 µm thick atop a borosilicate glass substrate of equal thickness. The atomic pair distribution function derived from the thin-film measurement is in excellent agreement with that from bulk measurements. This ability to measure the total scattering of amorphous organic thin films in transmission will enable accuratein situstructural studies for a wide range of materials.

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