Fabrication and Electrical Characterization of the Si/ZnO/ZnO:Al Structure Deposited by RF-Magnetron Sputtering A. ALAYA, 1,3 K. DJESSAS, 2 L. EL MIR, 1 and K. KHIROUNI 1 1.—Laboratoire de Physique des Mate ´riaux et des Nanomate ´riaux applique ´e a ` l’Environnement, Faculte ´ des Sciences de Gabe `s, Universite ´ de Gabe `s, Cite ´ Erriadh Manara Zrig, 6072 Gabe `s, Tunisia. 2.—Laboratoire de mathe ´matiques et physique des syste `mes (MEPS), Universite ´ de Perpignan, 52, Avenue Paul Alduy, 66860 Perpignan Cedex, France. 3.—e-mail: amel_alaya@yahoo.fr The electrical transport properties of the structures of Si(p)/ZnO(i)/ZnO: Al(3%) and Si(p)/PS/ZnO(i)/ZnO: Al(3%) deposited by radio-frequency-mag- netron sputtering were investigated and compared by using current–voltage and impedance spectroscopy measurements in a wide temperature range of 80–300 K. Aluminum-doped ZnO is considered to be one of the most important transparent conducting oxide materials due to its high conductivity, good transparency and low cost. From the current–voltage–temperature (I–V–T) characteristics, it was found that both structures had a good rectifying behavior. This behavior decreases according to the porous silicon layer. The variation of the conductance with frequency indicates the semiconducting behavior and superposition of different conduction mechanisms. The insertion of the porous silicon layer results in a decrease of conductivity, which is at- tributed to reduced conductivity of defect-rich porous silicon. Key words: Zinc oxide, porous silicon, thin films, sputtering INTRODUCTION Zinc oxide (ZnO), which belongs to the II–VI oxides family, has a very broad range of applica- tions, such as in transparent electrodes in solar cells, photovoltaics and optoelectronic devices, 1,2 due to its wide direct band gap energy of 3.37 eV and its large exciton binding energy of 60 meV 3 at room temperature. ZnO is usually an n-type semiconductor. ZnO thin films doped with group III elements have been used as transparent and conducting films. Aluminum- doped ZnO (AZO) is considered to be one of the most important transparent conducting oxide (TCO) materials due to its high conductivity, good trans- parency and low cost. Several methods have been used to deposit ZnO films, such as molecular beam epitaxy, 4 reactive evaporation, 5 pulsed laser depo- sition, 6 sol–gel processing 7 and radio-frequency (RF)-magnetron sputtering. 8 However, among these techniques, sputtering and sol–gel processing offered more advantages. Sputtering is a simple and low-cost technique that has a high deposition rate with no toxic gas emissions and is easy to expand to large-scale glass substrates. The sol–gel process is also a low-cost technique that enables researchers to easily design and fabricate a wide variety of materials and for the possibility of doping even at high concentrations. Both techniques can be complementary by using the synthesized sol–gel material as a target for sputtering thin film depo- sition, rather than the standard and expensive commercial sintered ceramics. To optimize the performance of a given optoelec- tronic device, especially on a generally multi-lay- ered photovoltaic solar cell structure, it is of primary importance to elucidate the optical and electrical properties of its individual layers and/or its partial structure. The aim of this work is to investigate the electri- cal properties of a partial solar cell structure consisting of a Si(p)/ZnO(i)/ZnO:Al(3%) hetero- structure and to study the effect of introducing a (Received February 25, 2015; accepted May 27, 2016) Journal of ELECTRONIC MATERIALS DOI: 10.1007/s11664-016-4705-0 Ó 2016 The Minerals, Metals & Materials Society