Vol. 8 & Issue 3 ; Section C : Physical Sciences

Date : May 2018 to July 2018

 

A theoretical study of optical properties of CdS quantum dots and evaluation of optical band gap of CdS nanoparticles, particle size and temperature dependent intensity of PL-spectra as a function of photon energy

Chandni Verma, Hari Sumiran Singh and L. K. Mishra,

JCBPS; Section C; May 2018 – July 2018, Vol. 8, No. 3; 201-214,

[DOI: 10.24214/jcbps.C.8.3.20114]

  • Abstract

    Using the theoretical formalism of N. Soltani etal [Chalcogenide Lett. 9, 321(2012)], N. Q. S. Sabir [Int. J. Nanosci. Nanotechnol. 8, 111 (2012)], P. Ghosh et al.. [arXiv:1606.06711v][cond-mat.mtrl-Sci] 21 June 2016 and Silan Baturang [J. BAUN Inst. Sci. Technol. 19, 264 (2017)], we have theoretically studied CdS nanoparticle and CdS QDs. We have evaluated energy band gap and particle size of fcc and hcp structure nanoparticle. Our theoretically obtained results show that particle size increases with increase of the irradiation times whereas energy band gap decreases with increase of irradiation times. The particle size obtained for hcp structure is large compared to fcc structure. We have evaluated time dependent PL-intensity as a function of photon energy for different temperature and Full width at half maximum (FWHM) broadening as a function of temperature. Our evaluated results show that temperature dependent PL-intensity increase, attain maximum value and then decrease as a function of photon energy for each temperature. However the maximum value of peak enhances as one increase the temperature. Our results of FWHM broadening as a function of temperature increase with temperature. The results show that the large no of relaxation processes are involved in this broadening.The dominant contribution comes from exciton-phonon coupling and ionized impurity scattering. Our theoretically evaluated results are in good agreement with those of the other theoretical workers.The entire evaluation in this paper is based on time independent Schrodinger equation with Density Functional method (DST), Brus equation and empirically established Varshni relation. These studies will be quite helpful in order to understand the different relaxations processes involved in light emission from CdS nanoparticle and CdS QDs. These are very important for future applications in photonic and optoelectronic devices