scholarly journals Electron tunneling in the germanium/silicon heterostructure with germanium quantum dots: theory

2021 ◽  
Vol 12 (4) ◽  
pp. 306-313
Author(s):  
S. I. Pokutnyi ◽  
◽  
N. G. Shkoda ◽  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Electron Tunneling ◽  
Infrared Range ◽  
Silicon Matrix ◽  
Electron States ◽  
A Chain ◽  
A Charge ◽  
Germanium Quantum Dots ◽  
Germanium Silicon

It is shown that electron tunneling through a potential barrier that separates two quantum dots of germanium leads to the splitting of electron states localized over spherical interfaces (a quantum dot – a silicon matrix). The dependence of the splitting values of the electron levels on the parameters of the nanosystem (the radius a quantum dot germanium, as well as the distance D between the surfaces of the quantum dots) is obtained. It has been shown that the splitting of electron levels in the QD chain of germanium causes the appearance of a zone of localized electron states, which is located in the bandgap of silicon matrix. It has been found that the motion of a charge-transport exciton along a chain of quantum dots of germanium causes an increase in photoconductivity in the nanosystem. It is shown that in the QD chain of germanium a zone of localized electron states arises, which is located in the bandgap of the silicon matrix. Such a zone of local electron states is caused by the splitting of electron levels in the QD chain of germanium. Moreover, the motion of an electron in the zone of localized electron states causes an increase in photoconductivity in the nanosystem. The effect of increasing photoconductivity can make a significant contribution in the process of converting the energy of the optical range in photosynthesizing nanosystems. It has been found that comparison of the splitting dependence of the exciton level Eех(а) at a certain radius a QD with the experimental value of the width of the zone of localized electron states arising in the QD chain of germanium, allows us to obtain the distances D between the QD surfaces. It has been shown that by changing the parameters of Ge/Si heterostructures with germanium QDs (radius of a germanium QD, as well as the distance D between the surfaces of the QDs), it is possible to vary the positions and widths of the zones of localized electronic states. The latter circumstance opens up new possibilities in the use of such nanoheterostructures as new structural materials for the creation of new nano-optoelectronics and nano-photosynthesizing devices of the infrared range.

scholarly journals Intensity of Radiative Recombination in the Germanium/Silicon Nanosystem with Germanium Quantum Dots

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 275
Author(s):  
Sergey I. Pokutnyi ◽  
Lucjan Jacak
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Radiative Recombination ◽  
Electron Transition ◽  
Real Space ◽  
Bandgap Energy ◽  
Silicon Matrix ◽  
Hole Energy ◽  
Germanium Quantum Dots ◽  
Germanium Silicon

It is shown that in a germanium/silicon nanosystem with germanium quantum dots, the hole leaving the germanium quantum dot causes the appearance of the hole energy level in the bandgap energy in a silicon matrix. The dependences of the energies of the ground state of a hole and an electron are obtained as well as spatially indirect excitons on the radius of the germanium quantum dot and on the depth of the potential well for holes in the germanium quantum dot. It is found that as a result of a direct electron transition in real space between the electron level that is located in the conduction band of the silicon matrix and the hole level located in the bandgap of the silicon matrix, the radiative recombination intensity in the germanium/silicon nanosystem with germanium quantum dots increases significantly.

scholarly journals Field Squeezing in a Quantum-Dot Molecule Jaynes-Cummings Model

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Xu Chu ◽  
Xiaodong Ma ◽  
Ying Wang ◽  
Qingchun Zhou ◽  
Yu Zhou
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Number Field ◽  
Electron Tunneling ◽  
Photon Number ◽  
Electron Interaction ◽  
Coherent Field ◽  
Physical Quantities

We investigate the field squeezing in a system composed of an initial coherent field interacting with two quantum dots coupled by electron tunneling. An approximate quantum-dot molecule Jaynes-Cummings model describing the system is given, and the effects of physical quantities, such as the temperature, phonon-electron interaction, mean photon number, field detuning, and tunneling-level detuning, are discussed in detail.

Quantum Confinement in the Spectral Response of n-Doped Germanium Quantum Dots Embedded in an Amorphous Si Layer for Quantum Dot-Based Solar Cells

2020 ◽  
Vol 3 (3) ◽  
pp. 2813-2821
Author(s):  
Jacopo Parravicini ◽  
Francesco Di Trapani ◽  
Michael D. Nelson ◽  
Zachary T. Rex ◽  
Ryan D. Beiter ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Solar Cells ◽  
Quantum Dot ◽  
Quantum Confinement ◽  
Spectral Response ◽  
Amorphous Si ◽  
Germanium Quantum Dots

Antiresonance of electron tunneling through a four-quantum-dot ring with two side-coupled quantum dots

2008 ◽  
Vol 372 (17) ◽  
pp. 3085-3088 ◽  
Author(s):  
Di Zhang ◽  
Jia-ning Ma ◽  
Hua Li ◽  
Shu-fang Fu ◽  
Xuan-Zhang Wang
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Electron Tunneling ◽  
Coupled Quantum Dots

scholarly journals Charge-tunnelling and self-trapping: common origins for blinking, grey-state emission and photoluminescence enhancement in semiconductor quantum dots

Nanoscale ◽  
2016 ◽  
Vol 8 (17) ◽  
pp. 9272-9283 ◽  
Author(s):  
M. A. Osborne ◽  
A. A. E. Fisher
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Carrier Dynamics ◽  
Semiconductor Quantum Dots ◽  
Self Trapping ◽  
Photoluminescence Enhancement ◽  
A Charge

Modelling quantum dot blinking, grey-states and photoluminescence enhancement within a charge-tunnelling and self-trapping description of exciton-carrier dynamics.

INTRINSIC AND EXTRINSIC DECOHERENCE FOR CHARGE QUBIT DYNAMICS IN A DOUBLE QUANTUM DOT

2014 ◽  
Vol 28 (02) ◽  
pp. 1450014
Author(s):  
LI WANG ◽  
TAO TU ◽  
GUO-PING GUO ◽  
GUANG-CAN GUO
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Double Quantum ◽  
Charge Qubit ◽  
Semiconductor Quantum Dot ◽  
Double Quantum Dot ◽  
Crucial Difference ◽  
A Charge ◽  
Environment Noise

In this paper, we investigate different decoherence sources with a charge qubit in a semiconductor quantum dot device. We distinguish between the intrinsic qubit population leakage and extrinsic environment noise, through a crucial difference in their signatures on the dynamics of the qubit. The results demonstrated here could help to develop unified understanding of decoherence mechanism in quantum dots and allow us to design suitable protocols for control and measurement.

scholarly journals Surface state-induced barrierless carrier injection in quantum dot electroluminescent devices

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hyeonjun Lee ◽  
Byeong Guk Jeong ◽  
Wan Ki Bae ◽  
Doh C. Lee ◽  
Jaehoon Lim
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Energy Landscape ◽  
Surface States ◽  
Hole Injection ◽  
Carrier Injection ◽  
Device Structure ◽  
Electroluminescent Devices ◽  
Potential Gain ◽  
A Charge

AbstractThe past decade has witnessed remarkable progress in the device efficiency of quantum dot light-emitting diodes based on the framework of organic-inorganic hybrid device structure. The striking improvement notwithstanding, the following conundrum remains underexplored: state-of-the-art devices with seemingly unfavorable energy landscape exhibit barrierless hole injection initiated even at sub-band gap voltages. Here, we unravel that the cause of barrierless hole injection stems from the Fermi level alignment derived by the surface states. The reorganized energy landscape provides macroscopic electrostatic potential gain to promote hole injection to quantum dots. The energy level alignment surpasses the Coulombic attraction induced by a charge employed in quantum dots which adjust the local carrier injection barrier of opposite charges by a relatively small margin. Our finding elucidates how quantum dots accommodate barrierless carrier injection and paves the way to a generalized design principle for efficient electroluminescent devices employing nanocrystal emitters.

scholarly journals Modelling of electronic and optical properties of Cu2SnS3 quantum dots for optoelectronics applications

2019 ◽  
Vol 37 (1) ◽  
pp. 108-115
Author(s):  
M. Irshad Ahamed ◽  
K. Sathish Kumar
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Solar Cell ◽  
Quantum Dot ◽  
Near Infrared ◽  
Infrared Range ◽  
Tin Sulfide ◽  
Bohr Radius ◽  
Energy Bandgap ◽  
Near Infrared Range

AbstractCopper tin sulfide (Cu2SnS3) is a unique semiconductor, whose nanocrystals have attracted researchers’ attention for its tunable energy bandgap and wavelength in visible and near infrared range. Quantum dots which are fabricated from this material are highly suitable for optoelectronics and solar cell applications. This paper discusses the tunable energy bandgap, exciton Bohr radius and wavelength range of wurtzite structure of Cu2SnS3 quantum dots to assess the opportunity to use them in optoelectronics applications. The considerations show that the mole fraction of copper increases as energy bandgap decreases and tunable energy bandgap of this quantum dot material is inversely proportional to the wavelength.

Sign in / Sign up

Export Citation Format

Share Document