Charge transfer and optical properties of wurtzite-type ZnS/(CdS/ZnS)n (n=2, 4, 8) superlattices

• Published in: Materials research bulletin Vol. 50; pp. 359 - 364
• Main Authors: Zeng, Xianghua, Zhang, Wei, Cui, Jieya, Zhou, Min, Chen, Haitao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2014
• Subjects: A. Multilayers; B. Laser deposition; C. Raman spectroscopy; D. Luminescence; D. Optical properties; C. Raman spectroscopy; A. Multilayers; B. Laser deposition; D. Luminescence; D. Optical properties
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2013.11.010

(a) Normalized temperature-dependent PL spectra of ZnS/(CdS/ZnS)4 superlattices from 5 to 300K and (b) schematic of charge transfer at CdS/ZnS interface. •Wurtzite ZnS/(CdS/ZnS)n superlattices were prepared at 100°C by pulsed laser deposition.•Surface phonon of ZnS and multiple phonons modes of ZnS and CdS were observed.•The charge transfer of electrons from CdS electron to ZnS holes by excitation energy was found. ZnS/(CdS/ZnS)n (n=2, 4, 8) superlattices were deposited on sapphire substrate by pulsed laser deposition (PLD) with alternate cadmium sulfide (CdS) and zinc sulfide (ZnS) crystals at 100°C. The prepared samples with an average thickness of ∼30nm for ZnS layer and ∼60nm for CdS layer have a wurtzite-type structure. Surface phonon of ZnS and multiple phonons modes for ZnS and CdS were observed from Raman spectra. PL spectra show a strong green emission at ∼496nm, two weak emission bands at ∼400 and ∼577nm, where the emission band at 400nm was attributed to the recombination of surface defects states to valence, the emission band at 577nm as the recombination of Cdi–VCd centers, and the strong emission at ∼496nm is from the charge transfer of electrons from CdS electron to ZnS holes by excitation energy.