Sample Concentration Affects Optical Gain Results in Colloidal Nanomaterials: Circumventing the Distortions by Below Band Gap Excitation

ACS Photonics ◽  
2021 ◽  
Author(s):  
Gabriel Nagamine ◽  
Tomas A. C. Ferreira ◽  
Diogo B. Almeida ◽  
Jonathan C. Lemus ◽  
Jun Hyuk Chang ◽  
...  
Keyword(s):  
Band Gap ◽  
Optical Gain ◽  
Sample Concentration

scholarly journals Ultrafast band-gap renormalization and build-up of optical gain in monolayer MoTe2

2020 ◽  
Vol 101 (7) ◽  
Author(s):  
L. Meckbach ◽  
J. Hader ◽  
U. Huttner ◽  
J. Neuhaus ◽  
J. T. Steiner ◽  
...  
Keyword(s):  
Band Gap ◽  
Optical Gain

High n-Type Doping in Ge for Optical Gain and Lasing

2013 ◽  
Vol 205-206 ◽  
pp. 394-399
Author(s):  
Yan Cai ◽  
Jurgen Michel
Keyword(s):  
Band Gap ◽  
Diffusion Mechanism ◽  
Optical Gain ◽  
Peak Shift ◽  
Ex Situ ◽  
High Doping Level ◽  
Enhanced Diffusion ◽  
Delta Doping ◽  
Direct Band ◽  
Band Gap Narrowing

We review two ex-situ doping methods to achieve high n-type doping up to mid-1019 cm-3 in Ge-on-Si thin films. For both, delta doping and ion implantation, rapid thermal annealing is used to diffuse phosphorus from a diffusion source into the single crystal Ge layer. The diffusion mechanism is studied and we find that dopant enhanced diffusion in in-situ doped Ge attributes to the high doping level. A band gap narrowing effect is observed in highly doped n-type Ge through photoluminescence measurements by determining the photoluminescence peak shift. An empirical linear expression of the direct band gap narrowing shift with carrier concentration is proposed.

Picosecond Dynamics of Optical Gain Duo to Electron-Hole Plasma in GaAs under Near Band-Gap Excitation

1983 ◽  
Vol 52 (2) ◽  
pp. 677-685 ◽  
Author(s):  
Shosaku Tanaka ◽  
Takaaki Kuwata ◽  
Takehiro Hokimoto ◽  
Hiroshi Kobayashi ◽  
Hiroshi Saito
Keyword(s):  
Band Gap ◽  
Optical Gain ◽  
Electron Hole ◽  
Hole Plasma ◽  
Electron Hole Plasma

Surface States and Band Gap Correlation in Silicon Nanoclusters

2015 ◽  
Vol 1107 ◽  
pp. 308-313
Author(s):  
Sib Krishna Ghoshal ◽  
M.R. Sahar ◽  
R. Arifin ◽  
M.S. Rohani ◽  
K. Hamzah
Keyword(s):  
Band Gap ◽  
Surface Passivation ◽  
Light Emission ◽  
Radiative Lifetime ◽  
Surface States ◽  
Optical Gain ◽  
Visible Luminescence ◽  
Optical And Electronic Properties ◽  
Effect Of Oxygen

Tuning the visible emission of Si nanomaterials by modifying their size and shape is one of the key issue in optoelectronics. The observed optical gain in Si-nanoclusters (NCs) has given further impulse to nanosilicon research. We develop a phenomenological model by combining the effects of surface passivation, exciton states and quantum confinement (QC). The size and passivation dependent band gap, oscillator strength, radiative lifetime and photoluminescence (PL) intensity for NCs with diameter ranging from 1.0 to 6.0 nm are presented. By controlling a set of fitting parameters, it is possible to tune the optical band gap, PL peak and intensity. In case of pure clusters, the band gap is found to decrease with increasing NC size. Furthermore, the band gap increases on passivating the surface of the cluster with hydrogen and oxygen respectively in which the effect of oxygen is more robust. Both QC and surface passivation in addition to exciton effects determine the optical and electronic properties of silicon NCs. Visible luminescence is due to radiative recombination of electrons and holes in the quantum-confined NCs. The role of surface states on the band gap as well as on the HOMO-LUMO states is also examined and a correlation is established. Our results are in conformity with other observations. The model can be extended to study the light emission from other nanostructures and may contribute towards the development of Si based optoelectronics.

Band-gap renormalization and optical gain formation in highly excited CdSe

1992 ◽  
Vol 117 (1-4) ◽  
pp. 732-737 ◽  
Author(s):  
Y. Masumoto ◽  
B. Fluegel ◽  
K. Meissner ◽  
S.W. Koch ◽  
R. Binder ◽  
...  
Keyword(s):  
Band Gap ◽  
Optical Gain

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

Structural properties of GaAs/InGaAs/GaAs (001) and InGaAs/GaAs (001) heterostructures and correlation with electronic properties

1990 ◽  
Vol 48 (4) ◽  
pp. 602-603
Author(s):  
J.M. Bonar ◽  
R. Hull ◽  
R. Malik ◽  
R. Ryan ◽  
J.F. Walker
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Gaas Substrate ◽  
Critical Thickness ◽  
Lattice Mismatch ◽  
Band Offset ◽  
Misfit Dislocations ◽  
Gaas Substrates ◽  
Gaas Structure ◽  
Low X

In this study we have examined a series of strained heteropeitaxial GaAs/InGaAs/GaAs and InGaAs/GaAs structures, both on (001) GaAs substrates. These heterostructures are potentially very interesting from a device standpoint because of improved band gap properties (InAs has a much smaller band gap than GaAs so there is a large band offset at the InGaAs/GaAs interface), and because of the much higher mobility of InAs. However, there is a 7.2% lattice mismatch between InAs and GaAs, so an InxGa1-xAs layer in a GaAs structure with even relatively low x will have a large amount of strain, and misfit dislocations are expected to form above some critical thickness. We attempt here to correlate the effect of misfit dislocations on the electronic properties of this material.The samples we examined consisted of 200Å InxGa1-xAs layered in a hetero-junction bipolar transistor (HBT) structure (InxGa1-xAs on top of a (001) GaAs buffer, followed by more GaAs, then a layer of AlGaAs and a GaAs cap), and a series consisting of a 200Å layer of InxGa1-xAs on a (001) GaAs substrate.

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