Tuning of optical and electrical properties of wide band gap Fe:SnO 2 /Li:NiO p–n junctions using 80 MeV oxygen ion beam Bhaumik V. Mistry 1 • D. K. Avasthi 2 • U. S. Joshi 1 Received: 23 April 2016 / Accepted: 26 October 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Abstract Electrical and optical properties of pristine and swift heavy ion (SHI) irradiated p–n junction diode have been investigated for advanced electronics application. Fe:SnO 2 /Li:NiO p–n junction was fabricated by using pulsed laser deposition on c-sapphire substrate. The optical band gaps of Fe:SnO 2 and Li:NiO films were obtained to be 3.88 and 3.37 eV, respectively. The current–voltage char- acteristics of the oxide-based p–n junction showed a rec- tifying behaviour with turn-on voltage of 0.95 V. The oxide-based p–n junction diode was irradiated to 80 MeV O ?6 ions with 1 9 10 12 ions/cm 2 fluence. Decrease in grain size due to SHI irradiation is confirmed by the grazing angle X-ray diffraction and atomic force micro- scopy. In comparison with the pristine p–n junction diode, O ?6 ion irradiated p-n junction diode shows the increase of surface roughness and decrease of percentage transmit- tance in visible region. For irradiated p–n junction diode, current–voltage curve has still rectifying behaviour but exhibits lower turn-on voltage than that of virgin p– n junction diode. 1 Introduction Materials exhibiting both high optical transparency in the visible range of the electromagnetic spectrum and high electrical conductivity are not common when considering the categories of conventional materials. Though, certain materials simultaneously fulfil the requirements of favourable conductivity and transparency. ‘‘Transparent electronics’’ is an emerging field of technology that employs wide band gap semiconductors for the realization of invisible circuits for next generation of optoelectronic devices such as amorphous and microcrystalline thin-film solar cells, gas sensors, and architectural window coatings [1–5]. An important criterion for materials that can be used in these applications is that they possess a high optical transparency in the visible range of the electromagnetic spectrum and high electrical conductivity. Combination of conductivity and transparency in oxides is achieved by fabricating them with a non-stoichiometric composition or by introducing appropriate dopants. Among various oxide semiconductors, tin oxide, zinc oxide, titanium oxide, nickel oxide are particularly attractive materials [2–8]. Most research to develop n-type conducting oxide films has focused on four compounds: In 2 O 3 , SnO 2 , CdO, and ZnO. In this work, Fe-doped SnO 2 was used as n-type conducting oxide. Because of its good adsorptive properties and chemical stability, it can be deposited on glass, ceramics, oxides, and substrate materials of other types. It has a high melting point and good transmission of light in visible region of electromagnetic spectra, and it does not easily react with oxygen and water vapour in the air, so it has a high specific volume and good cycling performance [9]. On the other hand, lithium-doped nickel oxide (Li:NiO) has been used as a p-type semiconductor. NiO is a wide band gap semiconductor at room temperature [10, 11]. It has been demonstrated that change in electric prop- erties can be induced by swift heavy ion irradiation (SHI) in binary oxides such as Li-doped NiO thin film [12] and In 2 O 3 thin film [13]. There are reports on irradiation effects on SnO 2 thin film for modifying its optical, electrical, & U. S. Joshi usjoshi@gmail.com 1 Department of Physics, School of Sciences, Gujarat University, Ahmedabad 380 009, India 2 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067, India 123 Appl. Phys. A (2016) 122:1024 DOI 10.1007/s00339-016-0518-5