Optical Properties of Mg-GaN, GaN/AlGaN SCH structures, and GaN on ZnO Substrates

ABSTRACTGaN films and GaN/AlGaN heterostructures have been gro wn by MBE. GaN films doped with varying levels of Mg indicate effective mass acceptor at low doping concentrations, as determined from strong photoluminescence emission at about 380 nm. As the Mg concentration is increased the photoluminescence emission line red shifts considerably, indicating the formation of Mg-related or induced complexes whose lifetimes are relatively short. GaN/AlGaN separate confinement heterostructures grown on sapphire show strong near ultraviolet stimulated emission at room temperature in a side-pumping configuration. The pumping threshold for stimulated emission at room temperature was found to be ∼90 kW/cm2. Initial GaN films grown on ZnO substrates show the A exciton in low temperature photoluminescence. ZnO is being considered for nitride growth because of its stacking order and close lattice match.

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Optical Properties of Doped Cd1−xMnxTe

MRS Proceedings ◽

10.1557/proc-89-281 ◽

1986 ◽

Vol 89 ◽

Author(s):

Y. Lansari ◽

N. C. Giles ◽

J. F. Schetzina ◽

P. Becia ◽

D. Kaiser

Keyword(s):

Optical Properties ◽

Low Temperature ◽

Spectral Range ◽

Room Temperature ◽

Far Infrared ◽

Optical Quality ◽

Structural Quality ◽

Reflectance Measurements ◽

Low Temperature Photoluminescence

AbstractThe introduction of phosphorus and arsenic dopants into bulk Cd1−xMnx Te crystals grown by the Bridgman-Stockbarger technique has been studieA-with respect to the resulting optical properties. Samples with a Mn composition in the range 0.10 < x < 0.30, both as-grown and annealed, were investigated. A combination of room temperature transmittance and reflectance measurements over the spectral range from the ultraviolet to the far infrared has been used to gain information concerning the structural quality of the samples. Low temperature photoluminescence measurements (1.6−5 K) were used to determine optical quality and excitonic energies.

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OPTICAL PROPERTIES OF CdTe/ZnTe ULTRATHIN QUANTUM WELLS GROWN BY ATOMIC LAYER EPITAXY

Surface Review and Letters ◽

10.1142/s0218625x02004189 ◽

2002 ◽

Vol 09 (05n06) ◽

pp. 1667-1670 ◽

Cited By ~ 7

Author(s):

M. GARCÍA-ROCHA ◽

I. HERNÁNDEZ-CALDERÓN

Keyword(s):

Optical Properties ◽

Low Temperature ◽

Quantum Wells ◽

Gaas Substrate ◽

Room Temperature ◽

Diffusion Length ◽

Substrate Surface ◽

Atomic Layer ◽

Atomic Layer Epitaxy ◽

Low Temperature Photoluminescence

Ultrathin quantum wells (UTQWs) of CdTe within ZnTe barriers were successfully grown by atomic layer epitaxy (ALE) on GaAs(001) substrates. ALE growth of CdTe was performed by alternate exposure of the substrate surface to individual fluxes of Cd and Te. Two different samples with 2-monolayer (ML) (substrate temperature Ts= 270° C ) and 4 ML (Ts = 290° C ) CdTe QWs were grown. Low temperature photoluminescence (PL) experiments exhibited intense and sharp peaks associated to the 2 ML QWs at 2.26 eV. In the case of the nominally 4-ML-thick QW the PL spectrum presented an intense peak around 2.13 eV and two weak features around 2.04 and 1.91 eV. The first peak is attributed to ~ 3 ML QW and the second one to ~ 4 ML QW. The dominance of the 3 ML peak is mainly attributed to Cd loss in the QW due to its substitution by Zn atoms. Due to a high diffusion length of the photogenerated carriers in the barriers, quite weak signals from the ZnTe barriers were observed in both cases. Room temperature (RT) photoreflectance (PR) spectra showed contributions from the CdTe UTQWs, the ZnTe barriers, and the GaAs substrate.

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Molecular Beam Epitaxy of Znl-x Cdx Se/ZnSe Heterostructures And Their Optical Properties

MRS Proceedings ◽

10.1557/proc-228-301 ◽

1991 ◽

Vol 228 ◽

Cited By ~ 5

Author(s):

H. Luo ◽

N. Samarth ◽

J. K. Furdyna ◽

H. Jeon ◽

J. Ding ◽

...

Keyword(s):

Optical Properties ◽

Molecular Beam Epitaxy ◽

Quantum Wells ◽

Room Temperature ◽

Molecular Beam ◽

Stimulated Emission ◽

Optically Pumped ◽

Absorption Coefficients ◽

Excitonic Absorption ◽

Lasing Mechanism

ABSTRACTSuperlattices and quantum wells of Znl-xCdxSe/ZnSe, and heterostructures based on ZnSe/CdSe digital alloys have been grown by molecular beam epitaxy (MBE). Their optical properties were studied with particular emphasis on excitonic absorption and photopumped stimulated emission. Excitonic absorption is easily observable up to 400 K, and is characterized by extremely large absorption coefficients (α = 2×105cm−1). Optically pumped lasing action is obtained at room temperature with a typical threshold intensity of 100 kW/cm2. The lasing mechanism in these II-VI quantum wells appears to be quite different from that in the better studied III-V materials: in our case, the onset of stimulated emission occurs before the saturation of the excitonic absorption, and the stimulated emission occurs at an energy lower than that of the excitonic absorption.

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Physical Properties of Thin Films of GaAs and AlxGa1-xAs Grown by Solid-Arsenic-Based MOCVD

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.976.25 ◽

2014 ◽

Vol 976 ◽

pp. 25-29

Author(s):

Roberto Castillo-Ojeda ◽

Joel Diaz-Reyes ◽

Miguel Galván-Arellano ◽

Ramon Peña-Sierra

Keyword(s):

Thin Films ◽

Optical Properties ◽

Fourier Transform ◽

Infrared Spectroscopy ◽

Low Temperature ◽

Growth Process ◽

Carbon Incorporation ◽

Infrared Measurements ◽

Hall Effect Measurements ◽

Low Temperature Photoluminescence

We have studied the optical properties of GaAs and AlxGa1-xAs thin films using low-temperature photoluminescence and Fourier transform infrared spectroscopy. The GaAs and its alloys were grown by MOCVD using solid arsenic instead of arsine, as the arsenic precursor. The gallium and aluminium precursors were trimethylgallium (TMGa) and trimethylaluminium (TMAl), respectively. Some difficulties for growing AlxGa1-xAs by solid-arsenic-based MOCVD system are the composition homogeneity of the layers and the oxygen and carbon incorporation during the growth process. The composition homogeneity of the films was evaluated by low-temperature photoluminescence. Infrared measurements on the samples allowed the identification of the residual impurities, which are carbon-substitutional, Ga2O3, molecular oxygen, humidity and two unidentified impurities. Samples grown at temperatures lower than 750°C were highly resistive, independently of the ratio V/III used; the samples grown at higher temperatures were n-type, as it was proved by Hall effect measurements.

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Electrical resistivity and photoluminescence of lead iodide crystals

Chemical Papers ◽

10.2478/s11696-006-0092-y ◽

2007 ◽

Vol 61 (1) ◽

Cited By ~ 8

Author(s):

M. Matuchová ◽

K. Žďánský ◽

M. Svatuška ◽

J. Zavadil ◽

O. Procházková

Keyword(s):

Electrical Resistivity ◽

Optical Properties ◽

Room Temperature ◽

Direct Synthesis ◽

Zone Melting ◽

Lead Iodide ◽

Electrical And Optical Properties ◽

X Ray ◽

Low Temperature Photoluminescence

AbstractDirect synthesis of lead iodide, a promising material for X-ray and γ detectors operating at room temperature, was developed and optimized. The influence of admixture of rare earth elements Ce, Ho, Gd, Yb, Er, and Tb in concentrations 0.05–0.5 at. % on the quality of prepared PbI2 was investigated. Zone melting was employed in order to increase the lead iodide purity. Electrical and optical properties of PbI2 samples were assessed on the basis of the measurement of electrical resistivity and low-temperature photoluminescence. The electrical resistivity of synthesized samples varied from 109 Ω cm to 1011 Ω cm and occasionally it was increased up to 1013 Ω cm.

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Heterogeneous Strain Relaxation in GaAs on Si (100)

MRS Proceedings ◽

10.1557/proc-116-251 ◽

1988 ◽

Vol 116 ◽

Cited By ~ 5

Author(s):

A. Freundlich ◽

G. Neu ◽

A. Leycuras ◽

R. Carles ◽

C. Verie

Keyword(s):

Residual Stress ◽

Low Temperature ◽

Room Temperature ◽

Strain Relaxation ◽

Photoluminescence Excitation ◽

X Ray Diffraction ◽

X Ray ◽

Si Substrates ◽

Low Temperature Photoluminescence ◽

Epilayer Surface

AbstractResidual stress in MOVPE grown GaAs on (100)Si substrates is investigated using Haman spectroscopy, X-ray diffraction, low temperature photoluminescence and photoluminescence excitation spectroscopy experiments. At room temperature, 2 µm-thick GaAs/Si is found to be under biaxial (100) tensile stress of X = 1.8 ± 0.3 kbar, near the epilayer surface. The stress magnitude decreases as the distance from interface decreases. PL and PLE studies on post-growth thermally annealed GaAs/Si reveal coexistence of unstrained and strained GaAs.

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Doping-Induced Room Temperature Stabilization of Metastable β-Ag2WO4 and Origin of Visible Emission in α- and β-Ag2WO4: Low Temperature Photoluminescence Studies

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.6b00078 ◽

2016 ◽

Vol 120 (13) ◽

pp. 7265-7276 ◽

Cited By ~ 34

Author(s):

Santosh Kumar Gupta ◽

Kathi Sudarshan ◽

Partha Sarathi Ghosh ◽

Saurabh Mukherjee ◽

Ramakant Mahadeo Kadam

Keyword(s):

Low Temperature ◽

Room Temperature ◽

Visible Emission ◽

Temperature Stabilization ◽

Photoluminescence Studies ◽

Low Temperature Photoluminescence

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Optical Properties of Self-Organized InGaAs/GaAs Quantum Dots in Field-Effect Structures

MRS Proceedings ◽

10.1557/proc-536-269 ◽

1998 ◽

Vol 536 ◽

Author(s):

A. Babinski ◽

T. Tomaszewicz ◽

A. Wysmolek ◽

J. M. Baranowski ◽

C. Lobo ◽

...

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Low Temperature ◽

Electric Field ◽

Field Effect ◽

Room Temperature ◽

Applied Bias ◽

Electric Field Dependence ◽

Self Organized ◽

Peak Energy

AbstractThe results of photoluminescence (PL) and electroreflectance (ER) measurements on InGaAs/GaAs self-organized quantum dots (QDs) in field-effect structure are presented. It has been found that the QDs PL can be completely quenched in reversely biased structure both at room temperature and at T=4.2K. A non-monotonic dependence of QDs PL peak energy with applied bias is observed at low temperature, which is attributed to the band-gap re-normalization due to QDs charging and size distribution effects. The electric field dependence of the QDs ER feature at room temperature has been analysed. A red shift of that feature with increasing electric field has been observed.

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