Structural and electrical characterizations of nanocrystalline Zn sub(1-x)Cd sub(x)S (0 less than or equal to x less than or equal to 0.9) prepared by low cost dip coating

• Published in: Materials science in semiconductor processing Vol. 24; pp. 169 - 178
• Main Authors: El-Wahidy, E F, Farag, AAM, Rafea, MAbdel, Roushdy, N, El-Shazly, O
• Format: Journal Article
• Language: English
• Published: 01.08.2014
• Subjects: Atomic force microscopy; Direct current; Fermi surfaces; Immersion coating; Mathematical models; Nanocrystals; Semiconductors; Thin films
• ISSN: 1369-8001
• DOI: 10.1016/j.mssp.2014.02.028

Thin films of nanocrystalline Zn sub(1-x)Cd sub(x)S (0 less than or equal to x less than or equal to 0.9) were deposited by a dip coating method on glass substrates from aqueous solution containing cadmium acetate, zinc acetate and thiourea at 200 degree C. The morphological, structural and electrical properties of the deposited Zn sub(1-x)Cd sub(x)S thin films were studied by atomic force microscopy (AFM), X-ray diffractometer (XRD), selected area electron diffraction (SAED) and photoluminescence (PL). To understand the predominant conduction mechanism of the nanocrystalline Zn sub(1-x)Cd sub(x)S (0 less than or equal to x less than or equal to 0.9) thin films, DC electrical conductivity was measured in the temperature range of 300-420 K. These measurements revealed that the DC behavior of the films can be described by a one-dimensional variable range hopping (VRH) model in the entire temperature range instead of a three-dimensional variable range hopping (VRH) model. The current density-voltage (J-V ) characteristics of Zn sub(1-x)Cd sub(x)S (0 less than or equal to x less than or equal to 0.9) thin films shows that the current conduction is ohmic type at the low-voltage region while the charge transport phenomenon appears to be space charge limited current (SCLC) at the higher-voltage regions. The latter conduction is attributed to the presence of a discrete trapping level. Various electrical parameters were determined and studied as a function of Cd-content such as electron mobility ( mu sub(0))( mu 0), density of states in conduction band (N sub(c)), Fermi energy (E sub(F)), trap energy (E sub(t)) and trap electron density (N sub(t)).