Copper sulphide (CuxS) as an ammonia gas sensor working at room temperature

Abstract

Abstract A solution growth technique (SGT) has been used to deposit Cu x S ( x = 1, 1.4, and 2) thin films on glass substrates at room temperature (300 K). These as-deposited thin films are characterized for their structural, optical and electrical properties by X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDAX), scanning electron microscopy (SEM) and atomic force microscopy (AFM), optical absorption and current–voltage ( I – V ) measurements. XRD shows that the Cu x S layer grew with hexagonal and monoclinic phases for x = 1 and 2, respectively. SEM and AFM show the nano-particles ( x = 1 and 1.4) and nano-discs ( x = 2) formation. The optical band gaps ( E g ) of thin films are 1.26 eV (CuS), 1.96 eV (Cu 1.4 S), and 2.31 eV (Cu 2 S). In addition, surface wettability is studied by using double-distilled water drops for contact angle measurements. It is observed that the contact angle for Cu 1.4 S is larger than those for CuS and Cu 2 S films. It suggests that the x = 1.4 films have high-surface energy. Ammonia gas sensors are fabricated by using these copper sulphide thin films with silver metal contacts. Based on the time-dependent experimental results nanostructured Cu x S serve as sensor material for the detection of NH 3 molecules at room temperature.