Appl Phys A (2014) 114:991–995 DOI 10.1007/s00339-013-8019-2 Effect of Cd content on the structural characteristic and some physical properties of Zn 1−x Cd x Se S.A. Gad · M. Boshta · A.M. Moustafa · A.M. Abo El-Soud Received: 6 July 2013 / Accepted: 2 October 2013 / Published online: 17 October 2013 © Springer-Verlag Berlin Heidelberg 2013 Abstract The present work focuses on the structural, op- tical, and electrical properties of Zn 1−x Cd x Se (0.1 ≤ x ≤ 0.25) compounds. The compounds were synthesized by solid state reaction. X-ray diffraction (XRD) patterns con- firm that the samples have cubic single phase (zinc-blende) crystal structure with space group F-43m. The crystal struc- tural parameters were refined by the Rietveld method using the FullProf program. It was found that the lattice param- eters increase linearly with increasing the Cd content and obeys Vegard’s law. The refined values of the crystallite size and the bond lengths increase with increasing the Cd con- tent. The energy band gap of the samples has been calcu- lated and it was found that it decreased as Cd increased. The conductivity of the samples increases with increasing both of composition parameter x and temperature, and showing semiconducting behavior. 1 Introduction Elements of II–VI compounds are attracting a great deal of attention because of their potential applications, ranging from optoelectronic devices such as light emitting diodes [1, 2], solar cells [3, 4], displays [5, 6], photovoltaic cells [7, 8] to luminescence biological tags [9, 10]. High absorp- tion coefficients, high efficiency of radiative recombination, and nearly matching band gaps with the visible region of the solar spectrum are the root causes of the popularity of II– VI group semiconductors. Their mixed II–VI ternary semi- conductors are used in optoelectronic devices ranging from S.A. Gad (B ) · M. Boshta · A.M. Moustafa · A.M. Abo El-Soud Solid State Physics Dept., National Research Center, El-Bohoos str., 12311 Dokki, Giza, Egypt e-mail: samiagad2000@yahoo.com blue to the near ultraviolet spectral region [9, 11]. In addi- tion, these materials are also used for manufacturing X-ray and γ -ray detectors [12, 13]. The Cd based compounds can also be used as an alterna- tive material for short and medium wavelength infrared focal plane arrays [13, 14]. ZnSe and CdSe which are members of the II–VI semiconductors are technologically important ma- terials due to their large direct band gap. Compositions near the CdSe end of the range have also been investigated as an alternative material to CdTe and CdSe in nuclear detectors since the large band gap of ZnCdSe should result in a less thermal generation of carriers with a consequent improve- ment in dark current and noise performance [15]. ZnSe compounds have cubic (zinc-blende) structure [16, 17], whereas CdSe compounds depending on the growth condition may have both cubic (zinc-blende) and hexagonal (wurtzite) structures at normal conditions. Bulk Zn x Cd 1−x Se crystallizes either in the cubic zinc-blende (x> 0.7) as well as in the hexagonal wurtzite structure (x< 0.5) or in mixture of these two structures for 0.5 ≤ x ≥ 0.7[18]. ZnCdSe, a wide band gap II–VI ternary compound semi- conductor, is an attractive material because its tunable band gap covers the visible spectrum, which is generally charac- terized in terms of its optical, electrical, and magnetic prop- erties [19–22]. In this study, the solid state reaction was used to prepare the Zn 1−x Cd x Se bulk with various Cd contents, and then employed X-ray diffraction (XRD) to analyze and refine the structure. The energy band gap was determined from the optical diffuse reflection and the activation energy from the electrical measurements. 2 Preparation Zn 1−x Cd x Se alloys with a different concentration of Cd (x = 0.1, 0.15, 0.2, and 0.25) were prepared by solid state