Optical Properties of Graphene Quantum Dots with Fractionally Filled Degenerate Shell of Zero Energy States

2011 ◽  
Author(s):  
A. D. Güçlü ◽  
P. Potasz ◽  
P. Hawrylak ◽  
Jisoon Ihm ◽  
Hyeonsik Cheong
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Quantum Dots ◽  
Zero Energy ◽  
Energy States

scholarly journals Electronic properties and quasi-zero-energy states of graphene quantum dots

2021 ◽  
Vol 103 (23) ◽  
Author(s):  
H. V. Grushevskaya ◽  
G. G. Krylov ◽  
S. P. Kruchinin ◽  
B. Vlahovic ◽  
Stefano Bellucci
Keyword(s):  
Quantum Dots ◽  
Electronic Properties ◽  
Graphene Quantum Dots ◽  
Zero Energy ◽  
Energy States

scholarly journals Zero-energy states in graphene quantum dots and rings

2011 ◽  
Vol 84 (15) ◽  
Author(s):  
C. A. Downing ◽  
D. A. Stone ◽  
M. E. Portnoi
Keyword(s):  
Quantum Dots ◽  
Graphene Quantum Dots ◽  
Zero Energy ◽  
Energy States

scholarly journals Theory of optical properties of graphene quantum dots

2015 ◽  
Vol 10 (1) ◽  
pp. 102-110 ◽  
Author(s):  
Isil Ozfidan ◽  
A. D. Güçlü ◽  
Marek Korkusinski ◽  
Pawel Hawrylak
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Quantum Dots

Tuning the electronic and optical properties of hexagonal boron-nitride nanosheet by inserting graphene quantum dots

2018 ◽  
Vol 32 (06) ◽  
pp. 1850084 ◽  
Author(s):  
Yi-Min Ding ◽  
Jun-Jie Shi ◽  
Min Zhang ◽  
Meng Wu ◽  
Hui Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Graphene Quantum Dots ◽  
Band Gaps ◽  
Hybrid Structures ◽  
Electronic And Optical Properties ◽  
Boron Nitride Nanosheet ◽  
Optoelectronic Nanodevices

It is difficult to integrate two-dimensional (2D) graphene and hexagonal boron-nitride (h-BN) in optoelectronic nanodevices, due to the semi-metal and insulator characteristic of graphene and h-BN, respectively. Using the state-of-the-art first-principles calculations based on many-body perturbation theory, we investigate the electronic and optical properties of h-BN nanosheet embedded with graphene dots. We find that C atom impurities doped in h-BN nanosheet tend to phase-separate into graphene quantum dots (QD), and BNC hybrid structure, i.e. a graphene dot within a h-BN background, can be formed. The band gaps of BNC hybrid structures have an inverse relationship with the size of graphene dot. The calculated optical band gaps for BNC structures vary from 4.71 eV to 3.77 eV, which are much smaller than that of h-BN nanosheet. Furthermore, the valence band maximum is located in C atoms bonded to B atoms and conduction band minimum is located in C atoms bonded to N atoms, which means the electron and hole wave functions are closely distributed around the graphene dot. The bound excitons, localized around the graphene dot, determine the optical spectra of the BNC hybrid structures, in which the exciton binding energies decrease with increase in the size of graphene dots. Our results provide an important theoretical basis for the design and development of BNC-based optoelectronic nanodevices.

The Role of Reduced Graphene Oxide Concentration as Ablated Material on Optical Properties of Graphene Quantum Dots

2019 ◽  
Vol 948 ◽  
pp. 267-273 ◽  
Author(s):  
Fiqhri Heda Murdaka ◽  
Ahmad Kusumaatmaja ◽  
Isnaeni ◽  
Iman Santoso
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Oxide ◽  
Band Gap ◽  
Reduced Graphene Oxide ◽  
Optical Band Gap ◽  
Graphene Quantum Dots ◽  
Absorption Peak ◽  
Oxygen Defect ◽  
Reduced Graphene

We report the synthesize of Graphene Quantum Dots (GQDs) using ablation method with reduced Graphene Oxide (rGO) solution as a starting material. We have varied the concentration of rGO as following: 0.5, 2, 5 mg/ml and then have ablated them using 800 nm Ti-Sapphire femtosecond laser to obtain GQDs. From the UV-Vis data, we observed that the more concentration of rGO is being ablated, the more secondary absorption peak at 255.1 nm appeared. This secondary absorption peak is a characteristic of n-π* bonding due to the presence of oxygen defect which occurs as a result of the interaction between the laser and the water in rGO solution. We conclude that the population of oxigen defect in GQDs is increasing, following the increase of rGO concentration and could alter the optical properties of GQD. On the other hand, using Tauc’s plot, we confirm that the increase of rGO concentration as the ablated material does not alter GQDs optical band gap. However, it will slightly reduce both, direct and indirect Oxygen defect related optical band gap.

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