American Journal of Optics and Photonics 2014; 2(6): 69-74 Published online January 14, 2015 (http://www.sciencepublishinggroup.com/j/ajop) doi: 10.11648/j.ajop.20140206.11 ISSN: 2330-8486 (Print); ISSN: 2330-8494 (Online) Electrical and photoelectrical properties of copper(II) complex/n-Si/Au heterojunction diode Cihat Ozaydin 1 , Kemal Akkilic 2 1 Department of Physics, Faculty of Science and Art, University of Batman, Batman, Turkey 2 Department of Physics, Faculty of Education, University of Dicle, 21280 Diyarbakır, Turkey Email address: Cihat.ozaydin@batman.edu.tr (C. Ozaydin), kakkilic@dicle.edu.tr (K. Akkilic) To cite this article: Cihat Ozaydin, Kemal Akkilic. Electrical and Photoelectrical Properties of Copper (II) Complex/n-Si/Au Heterojunction Diode. American Journal of Optics and Photonics. Special Issue: Organic Photonics & Electronics. Vol. 2, No. 6, 2014, pp. 69-74. doi: 10.11648/j.ajop.20140206.11 Abstract: In this study, we fabricated copper(II) complex/n-Si/Au organic-inorganic heterojunction diode by forming copper(II) complex thin film on n-type silicon. A direct optical band gap energy values of the copper(II) complex (Cu 2 C 34 H 34 N 2 O 21 Cl 4 ) thin film on a glass substrate was obtained as E g =2.98 eV. The current-voltage (I-V) measurement of the diode was carried out at room temperature and under dark. The ideality factor n and barrier height ϕ b values of the diode were found to be 3.17 and 0.71 eV, respectively. The diode indicates non-ideal current-voltage characteristics due to the high ideality factor greater than unity. The series resistance R s and ideality factor n values were determined using Cheung’s method and obtained as 5.54 kΩ and 3.81, respectively. The capacitance-voltage (C-V) measurements of the diode were performed at different frequency and room temperature. From the analysis of the C-V measurements carrier concentration N d , diffusion potential V d and barrier height values ϕ b c-v were determined as 2.79x10 15 cm -3 , 1.078 V, 1.31 eV, respectively. From the I-V measurements of the diode under 1.5 AM illumination, short circuit current (I sc ) and open circuit voltage (V oc ) have been extracted as 12.8 µA and 153 mV, respectively. Keywords: Organic-İnorganic, Heterojunction, Schottky Contact, Photovoltaic Properties 1. Introduction Organic materials have received increasing attraction as they possess interesting properties compared with the conventional inorganic semiconductors. Recent extensive studies have shown that organic materials exhibit a variety of interesting optical, electrical, and photoelectric properties in solid state physics [1]. Organic materials have been chosen in the fabrication of devices because of their some advantages such as low cost and easy preparation techniques, possibility of synthesis for different purposes and large area coverage [2]. The main advantages of these compounds may be chemical adjustability of their band gap and transport properties. So it is very important to find suitable organic compounds to fabricate electronic and optoelectronic devices based on organic materials. There are a number of ways to use organic molecules in the fabrication of electronic and optoelectronic devices. Organic–inorganic (OI) structure is one of them [3]. Many authors have fabricated this kind of structures to benefit from advantages of both organic and inorganic materials in a single device and modify electrical and photoelectrical properties of metal–semiconductor (MS) devices [4–7]. OI structures have been used as solar cells [8–10], light emitting diodes [11–12], Schottky diodes [13–15], etc. Organic/ inorganic semiconductor heterojunctions investigated both due to the unusual nature of these contacts as well as to the potential new devices applications. Organic semiconductors exhibit rectification behavior when deposited onto inorganic semiconductor substrates [16]. In this study, we have used recently synthesized [17] binuclear copper(II) complex with [Cu 2 (L)(ClO 4 ) 2 ][ClO 4 ] 2 (L is C 34 H 34 N 2 O 5 ) molecular formula as an organic material due to being rich conjugated electrons. The molecular structure of the copper(II) complex is shown in Fig. 1. Our aim is to fabricate a copper(II) complex/n-Si/Au OI structure to observe whether or not it can be used as a rectifying contact and to determine the electrical and photoelectrical properties of the device by investigating current–voltage under dark an illumination. To discuss how the diffusion potential is generated we measured the capacitance–voltage characteristics.