Zinc sulfide (ZnS) thin films have been prepared by chemical bath deposition method with improving growth rate and morphology using the mixed complexing agents of ethylenediamine tetra-acetate disodium salt (Na2EDTA) and hexamethylenetetramine (HMTA). The effects of HMTA quantity on the morphological, compositional, optical, structural and electrical properties of ZnS thin films with fixed Na2EDTA concentration have been investigated. ZnS thin films were deposited on glass substrates using aqueous solutions containing zinc acetate dehydrate and thioacetamide in acidic medium (pH 4). Field emission scanning electron microscopy results show that the morphology of a deposited ZnS thin film using HMTA as a complexing agent is rough. However, very uniform and smooth ZnS thin films are obtained using mixed complexing agents of Na2EDTA and HMTA. The growth rate and root mean square of ZnS thin films are improved with increasing HMTA quantities. X-ray diffraction patterns show that all the ZnS thin films are grown as a hexagonal structure without secondary phase (ZnO) regardless of HMTA quantity. Optical band gap energy of ZnS thin films deposited using mixed complexing agents increase from 3.75 to 3.87eV with increasing quantity of HMTA.
Bibliographical noteFunding Information:
This research was partially supported by a Grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy (10037233) and partially supported Ho-Nam Leading industry office through the Leading industry Development for Economic Region and partially by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MEST) (No. 2011-0001002).
Copyright 2011 Elsevier B.V., All rights reserved.
- Acidic medium
- Chemical bath deposition
- Growth rate
- Less toxic complexing agent
- ZnS thin films