Vol.:(0123456789) 1 3 Journal of Materials Science: Materials in Electronics https://doi.org/10.1007/s10854-018-0166-y Deposition and study of AZO heterojunction Schottky diodes at diferent temperatures Manisha R. Singh 1  · Km Sucheta Singh 1  · Shubhra Aakanksha 1  · Mohit Sahni 2  · Bhaskar Bhattacharya 2,3  · Pallavi Gupta 1  · Naresh Kumar 4 Received: 15 June 2018 / Accepted: 4 October 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Highly transparent AZO (Al 0.02 Zn 0.98 O) flms were deposited on p-type Si (100) using RF magnetron sputtering and then sintered at diferent temperatures (100 °C, 300 °C, 500 °C, and 600 °C). Structural properties of these flms were analyzed and compared using XRD, SEM and AFM. Further, this work investigates the electrical properties of diferent types of Schottky junctions made with Gold metal contacts on these thin flms. With the increasing fabrication temperature, both the optical band gap as well as the ideality factor were found to be decreasing. Impact of temperature variation on potential barrier of Schottky diodes and carrier concentration were also studied. 1 Introduction Many advanced devices are fabricated (e.g. ReRAM, Schottky diode, piezoelectric, and solar cell etc.) using ZnO thin flms [1–4]. Biocompatible and environment friendly material ZnO is a direct band gap (~ 3.37 eV at room tem- perature) semiconductor. ZnO has high (~ 60 meV) exciton binding energy which is comparatively better than that of ZnSe and GaN. ZnO has structural, optical as well as elec- trical characteristics which can be modifed by doping with diferent ions (like Al, Ga, and In etc). Due to the presence of native defects, undoped ZnO represents the characteristics of n-type semiconductor [5, 6]. ZnO has a demerit of high electrical resistivity which can be overcome by doping of ZnO with Al. AZO (Al doped ZnO) is a promising material as a transparent conductor [7–11]. Aluminum is light weight material with lower density (~ 2.7 g/mL). Al doping is more preferred as it has lower cost and small ionic radius. To make the Schottky diode, diferent metals (like Au, Pd, Ag, and Al etc.) can be used to make contacts. Demonstration of ZnO thin flm based low power UV photo detectors with Au/Pd Schottky contact was done by Varma et al. [12]. Schottky diode, with a low forward voltage drop and fast switching action leads to fast recovery time with an increase in efciency. Low voltage drop results in less wastage of power in comparison of p–n junction diode. This work shows the fabrication process of Schottky diode and a comparative study on structural, optical and electrical properties of Al doped ZnO at diferent substrate temperatures (100 °C, 300 °C, 500 °C, and 600 °C). The electrical parameters like η (ideality factor) and ϕ b (potential barrier) were calculated from the I–V measurement using conventional thermionic emission theory method. Further, the optical band gap was analyzed by Tauc model [13]. C–V analysis was also done to calculate the precise value of potential barrier [14]. 2 Experimental work 2.1 Thin flm fabrication The standard cleaning process RCA1 and RCA2 was used to clean Si (100) substrates [14]. We have used 99.999% pure targets of AZO, and Gold sourced from Sigma Aldrich. AZO thin flm having the thickness of 150 nm was depos- ited on cleaned Si (100) substrates using RF magnetron * Mohit Sahni mohitsahnihit@gmail.com 1 School of Engineering and Technology, Sharda University, Greater Noida, UP 201310, India 2 School of Basic Sciences and Research, Sharda University, Greater Noida, UP 201310, India 3 Department of Physics, MMV, Banaras Hindu University, Varanasi 221005, India 4 Department of Physics, MNNIT Allahabad, Allahabad 211004, India