Electron–hole transition energy for a spherical quantum dot confined in a nano-cylindrical wire

2011 ◽  
Vol 44 (3) ◽  
pp. 728-732 ◽  
Author(s):  
Gh. Safarpour ◽  
M. Barati ◽  
M.R.K. Vahdani
Keyword(s):  
Quantum Dot ◽  
Transition Energy ◽  
Electron Hole ◽  
Spherical Quantum Dot ◽  
Hole Transition ◽  
Cylindrical Wire

scholarly journals Uncorrelated electron-hole transition Energy in GaN│InGaN│GaN Spherical QDQW Nanoparticles

2013 ◽  
Vol 23 (2) ◽  
pp. 127 ◽  
Author(s):  
Haddou El Ghazi ◽  
Anouar Jorio ◽  
Izeddine Zorkani
Keyword(s):  
Turning Point ◽  
Transition Energy ◽  
Critical Value ◽  
Composition Effect ◽  
Electron Hole ◽  
Indium Composition ◽  
Hole Energy ◽  
Mass Approximation ◽  
Parabolic Potential ◽  
Hole Transition

The electron (hole) energy and uncorrelated \(1S_e - 1S_{h}\) electron-hole transition in Core(GaN)| well(In\(_x\)Ga\(_{1 - x}\)N)| shell(GaN) spherical QDQW nanoparticles is investigated as a function of the inner and the outer radii. The calculations are performed within the framework of the effective-mass approximation and the finite parabolic potential confinement barrier in which two confined parameters are taking account. The Indium composition effect is also investigated. A critical value of the outer and the inner ratio is obtained which constitutes the turning point of two indium composition behaviors. 

Electroreflectance Study of Porous Silicon made from Substrates with Different Resistivities

2000 ◽  
Vol 638 ◽  
Author(s):  
Toshihiko Toyama ◽  
Yasuharu Nakai ◽  
Hiroaki Okamoto
Keyword(s):  
Crystal Size ◽  
Transition Energy ◽  
Optical Transitions ◽  
Porous Si ◽  
Electron Hole ◽  
Si Substrates ◽  
Spherical Quantum Dot ◽  
Spectral Changes ◽  
Mass Approximation ◽  
Si Nanocrystals

AbstractEmploying electroreflectance (ER) spectroscopy, we have studied optical transitions in porous Si (PSi) with a thickness of 100±50 nm made from crystalline Si (c-Si) substrates with different resistivities, 4–10 ωcm (p-), 0.1–1 ωcm (p), and < 0.018 ωcm (p+). The ER features observed at 1.1–2.8 eV in p+ PSi are analyzed with a simple effective mass approximation (EMA) model for confined electron-hole (e-h) pairs in a spherical quantum dot as we have previously done for those observed at 1.2–3.1 eV in p- PSi. From the ER analysis with the EMA model, the effective crystal size is estimated without destruction, and the kinetic energy and the Coulomb attraction energy of the confined e-h pairs are also deduced.Furthermore, the ER features corresponding to the optical transitions at E1(E0') critical point (CP) are observed at 2.8–3.3 eV in p+ PSi. With an increase in the crystal size, the transition energy of E1(E0') CP in p+ PSi is decreased, while that in p- and p PSi is unchanged from that of 3.4 eV found in c-Si including the p+c-Si. From the Raman results, strain- and disorder-induced spectral changes are found to be negligible, so that the high doping induced effect is the most acceptable mechanism for the red-shift in E1(E0') transitions of Si nanocrystals with the crystal size of 2–3 nm.

scholarly journals Adjustment of Terahertz Properties Assigned to the First Lowest Transition of (D+, X) Excitonic Complex in a Single Spherical Quantum Dot Using Temperature and Pressure

2021 ◽  
Vol 11 (13) ◽  
pp. 5969
Author(s):  
Noreddine Aghoutane ◽  
Laura M. Pérez ◽  
Anton Tiutiunnyk ◽  
David Laroze ◽  
Sotirios Baskoutas ◽  
...  
Keyword(s):  
Refractive Index ◽  
Quantum Dot ◽  
Energy Region ◽  
Practical Importance ◽  
High Energy ◽  
Spherical Quantum Dot ◽  
Terahertz Region ◽  
Mass Approximation ◽  
Optical Responses ◽  
Temperature And Pressure

This theoretical study is devoted to the effects of pressure and temperature on the optoelectronic properties assigned to the first lowest transition of the (D+,X) excitonic complex (exciton-ionized donor) inside a single AlAs/GaAs/AlAs spherical quantum dot. Calculations are performed within the effective mass approximation theory using the variational method. Optical absorption and refractive index as function of the degree of confinement, pressure, and temperature are investigated. Numerical calculation shows that the pressure favors the electron-hole and electron-ionized donor attractions which leads to an enhancement of the binding energy, while an increasing of the temperature tends to reduce it. Our investigations show also that the resonant peaks of the absorption coefficient and the refractive index are located in the terahertz region and they undergo a shift to higher (lower) therahertz frequencies when the pressure (temperature) increases. The opposite effects caused by temperature and pressure have great practical importance because they offer an alternative approach for the adjustment and the control of the optical frequencies resulting from the transition between the fundamental and the first excited state of exciton bound to an ionized dopant. The comparison of the optical properties of exciton, impurity and (D+,X) facilitates the experimental identification of these transitions which are often close. Our investigation shows that the optical responses of (D+,X) are located between the exciton (high energy region) and donor impurity (low energy region) peaks. The whole of these conclusions may lead to the novel light detector or source of terahertz range.

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