Vol.:(0123456789) 1 3 Applied Physics A (2019) 125:372 https://doi.org/10.1007/s00339-019-2663-0 Efect of Cu doping concentration on H 2 S gas‑sensing properties of Cu‑doped SnO 2 thin flms Pankaj S. Kolhe 1  · Sunil G. Kulkarni 1  · Namita Maiti 2  · Kishor M. Sonawane 1 Received: 13 September 2018 / Accepted: 24 April 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Metal oxide-based gas sensors doped with metal element have attracted many researchers due to their enhancement in physico-chemical properties as compared to pristine counterpart. Herein, a novel idea of tailoring the structure and prop- erties by controlling the doping percentage is used to obtain the optimum performance characteristics. The present com- munication reports synthesis of pristine SnO 2 and in situ Cu-doped SnO 2 flms using simple chemical spray pyrolysis technique to study H 2 S gas-sensing characteristics. The synthesized pristine and Cu-doped SnO 2 flms were characterized using X-ray difraction (XRD), scanning electron microscopy (SEM) and UV–visible spectroscopy to reveal their structural, morphological, and optical properties, respectively. To ascertain the presence of CuO/SnO 2 interface, transmission electron microscopy (TEM) is carried out. Optimum doping concentration and operating temperature is determined by studying the gas-response characteristics for various doping concentrations at diferent operating temperatures. For this combination of optimum doping concentration and operating temperature, repeatability as well as response and recovery time towards H 2 S gas are systematically studied. 1 Introduction Metal oxide semiconductors have attracted more attention of researches in recent time because of their excellent physico- chemical properties and become potential candidates to fnd the application in various felds such as electronic, optical, optoelectronic felds [1]. Particularly, SnO 2 , ZnO, and TiO 2 which possess a wide energy bandgap, tremendous electrical conductivity and optical transparency make them vital mate- rials in feld of electronic devices [2]. Among the variety of metal oxide semiconductors, Tin dioxide (SnO 2 ) is acknowl- edged as one of the suitable material for multifunctional applications. The excellent chemical, electrical properties and wide bandgap (3.6 eV), native oxygen vacancies and high carrier density of SnO 2 are the main reason of being a potential material to be used in solar cell, lithium-ion rechargeable batteries, feld emitter and gas sensor appli- cations [3–5]. Moreover, SnO 2 is cost efective, physically stable and can be operated at wide range of temperatures; therefore it becomes most reliable material in feld of gas sensing to detect and monitor variety of pollutant and toxic gases such as CO, NH 3 , H 2 S etc. [6–8]. As a known fact, hydrogen sulfde (H 2 S) is highly toxic, bad smelling; fammable gas, can cause irritation to respira- tory tract, nausea and is dangerous to human health. It is produced as a by-product in laboratories and pharmaceuti- cal industry. Above 250 ppm level, the H 2 S gas can cause neurobehavioral toxicity and may even cause death [9]. Therefore, much attention has been given to detect H 2 S gas. However, SnO 2 as a gas sensor has encountered by many drawbacks such as slow response, low sensitivity and very high operating temperatures. To improve the gas-sensing performance of the sensor, researchers have functionalized the SnO 2 . For that purpose several approaches have been employed such as decorating SnO 2 nanostructure with metal particle [10, 11], forming nanocomposite with other metal oxide semiconductor [12, 13]. Doping metallic element impurities such as Ni, Pd, Ru, Cu etc. into SnO 2 is regarded as an efective approach to tailor the electronic properties Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00339-019-2663-0) contains supplementary material, which is available to authorized users. * Kishor M. Sonawane kmsonawane@gmail.com 1 Deparment of Physics, Fergusson College Afliated Savitribai Phule Pune University, Pune 411004, India 2 Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India