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Photoelectrical characterization of nanocrystalline AgBiS2 thin films

D. NESHEVA1,* , Z. ANEVA1, B. PEJOVA2, I. GROZDANOV2, A. PETROVA3

Affiliation

  1. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
  2. Institute of Chemistry, Faculty of Natural Sciences and Mathematics,Sts. Cyril and Methodius University, POB 162, 1000 Skopje, Macedonia
  3. Space Research Institute, Bulgarian Academy of Sciences, P.O. Box 799, 1000 Sofia, Bulgaria

Abstract

The photoelectric properties of chemically produced nanostructured AgBiS2 thin films are investigated. Atomic force microscopy is used to prove the nanocrystalline structure of the films, and a value of ~ 10 nm is obtained as an upper limit for the average grain size. The temperature dependences of the photocurrent measured in the range 77 – 390 K do not display high photosensitivity at low temperatures. This observation is related to a high density of fast recombination centers created at the interfaces between the nanocrystals. Persistent photoconductivity is measured at low-temperatures after turning off the light, and a high voltage polarization is observed on light illumination of the films. Both effects are related to trapping of photoexcited carriers in deep defect states, and are considered as responsible for the rather low value (< 0.5) of the exponent in the photocurrent intensity dependence. Constant photocurrent method measurements, carried out at energies higher than the optical band gap, reveal fine structure in the absorption spectra of the films, which could be assigned to higher excitons in AgBiS2 quantum dots, and be considered as an indication of a narrow size distribution of the nanocrystals in the layers..

Keywords

AgBiS2 thin films, Nanocrystals, Photocurrent.

Submitted at: Nov. 5, 2008
Accepted at: Sept. 9, 2009

Citation

D. NESHEVA, Z. ANEVA, B. PEJOVA, I. GROZDANOV, A. PETROVA, Photoelectrical characterization of nanocrystalline AgBiS2 thin films, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 9, pp. 1347-1350 (2009)