Investigation of the quantum well width on the size effect of PbSe/ZnSe multiple quantum well structures by non-epitaxial growth

Arivazhagan, V.; Parvathi, M. Manonmani; Rajesh, S.

doi:10.1016/j.jallcom.2013.06.135

Cited by 3 publications

(1 citation statement)

References 23 publications

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“…Since the beginning of the twentieth century, there has been a strong interest in thin films of lead-chalcogenide PbX (X = S, Se, Te) compounds. With the developments in solid-state physics and chemistry in the second half of the twentieth century, PbX thin films and later on also quantum wells were developed and extensively investigated. ,,,− Because of their small band gap (in the few 100 meV range), these systems have importance for optoelectronic applications in the near-IR as photon detectors.…”

Section: Study Of the Energy Levels Of Quantum Dots And Quantum Dot A...mentioning

confidence: 99%

Scanning probe microscopy and spectroscopy of colloidal semiconductor nanocrystals and assembled structures

2016

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Colloidal semiconductor nanocrystals become increasingly important in materials science and technology, due to their optoelectronic properties that are tunable by size. The measurement and understanding of their energy levels is key to scientific and technological progress. Here we review how the confined electronic orbitals and related energy levels of individual semiconductor quantum dots have been measured by means of scanning tunneling microscopy and spectroscopy. These techniques were originally developed for flat conducting surfaces, but they have been adapted to investigate the atomic and electronic structure of semiconductor quantum dots. We compare the results obtained on colloidal quantum dots with those on comparable solid-state ones. We also compare the results obtained with scanning tunneling spectroscopy with those of optical spectroscopy. The first three sections provide an introduction to colloidal quantum dots, and a theoretical basis to be able to understand tunneling spectroscopy on dots attached to a conducting surface. In sections 4 and 5 , we review the work performed on lead-chalcogenide nanocrystals and on colloidal quantum dots and rods of II-VI compounds, respectively. In section 6 , we deal with colloidal III-V nanocrystals and compare the results with their self-assembled counter parts. In section 7 , we review the work on other types of semiconductor quantum dots, especially on Si and Ge nanocrystals.

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Section: Study Of the Energy Levels Of Quantum Dots And Quantum Dot A...mentioning

confidence: 99%

Scanning probe microscopy and spectroscopy of colloidal semiconductor nanocrystals and assembled structures

2016

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Raman scattering in lead selenide films at a low excitation level

et al. 2015

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Photoacoustic and surface photovoltaic characteristics of L-Cysteine-capped ZnSe quantum dots with a core-shell structure

Ying-Ying¹,

Li²,

Qing-Song³

et al. 2016

Acta Phys. Sin.

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The study on photoelectronic characteristics of ZnSe quantum dots (QDs) is of significance for investigating its microelectronic structure and expanding its potential applications because ZnSe QD has low biologic toxicity. In the present paper, the surface photovoltaic and photoacoustic technologies, and laser Raman, X-ray diffraction, transmission electron microscopy and Foureier transform infrared spectroscopy spectrum are jointly used to probe the microstructures, the photoacoustic and surface photovoltaic characteristics of L-Cysteine-capped ZnSe QDs prepared by water-phase synthesis at different reflux temperatures. The results indicate that the ZnSe QDs with a mean grain size of about 3 nm has a core-shell ZnSe/ZnS/L-Cys structure, in which the sulfhydryl groups in ligand prefer reacting with Zn atom at the (220) face to form the ZnS shell layer between the core-ZnSe and ligand L-Cys. The results show that the QDs with n-type photovoltaic property display a wide range of surface photovoltaic response and weak photoacoustic signal upon the illumination of near ultraviolet to visible light as compared with others QDs with similar core-shell structures in II-VI group. Especially, the strong SPV response and the weak PA signal in a wavelength region of 350-550 nm imply that the photon energies in the range are almost all used to produce the surface photovoltaic (SPV) phenomenon instead of the thermal lattice vibration caused by non-radiative de-excitation process. This reveals the energy complementary relationship between the photoacoustic and the surface photovoltaic phenomena of the QDs. The PA signals appearing in a short wavelength range of 300-350 nm and the Raman peaks located in a high frequency ranges of 1120 cm-1, 1340 cm-1 and 1455 cm-1 are identified as relating closely to the multi-phonon vibration modes of ligand L-Cys. At low reflux temperature, the photoelectric threshold of the SPV response that relates to the core-ZnSe displays a red shift to a certain extent as compared with the bulk ZnSe. The narrowed bandgap may be attributed to quantum confinement effect of the QDs. In addition, the intensity of the SPV response that relates to the core-ZnSe gradually increases with the decrease of the reflux temperature. The results show that the above improved surface photovoltaic characteristics of the QDs may benefit from the reduced average grain size of the ZnSe QDs, thus causing its surface and small-size effects.

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Investigation of the quantum well width on the size effect of PbSe/ZnSe multiple quantum well structures by non-epitaxial growth

Cited by 3 publications

References 23 publications

Scanning probe microscopy and spectroscopy of colloidal semiconductor nanocrystals and assembled structures

Scanning probe microscopy and spectroscopy of colloidal semiconductor nanocrystals and assembled structures

Raman scattering in lead selenide films at a low excitation level

Photoacoustic and surface photovoltaic characteristics of L-Cysteine-capped ZnSe quantum dots with a core-shell structure

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