Investigation of particle size-dependent charge transport phenomena in copper sulphide (CuS) synthesized via solvothermal and co-precipitation methods.

In this present work, copper (II) sulfide (CuS) nanoparticles (NPs) were synthesized via co-precipitation [CuS(co-pr)] and solvothermal [CuS(solv)] methods. The structural, optical, and electrical properties of these materials were analyzed and compared. It was observed that the particle size and crystallinity varied depending on the synthesis method employed. Further, two individual metal-semiconductor junction devices based on CuS(co-pr) and (CuS(solv) were fabricated. Then the current vs. voltage (I–V) measurements were performed. The comparative study of the electrical parameters like photo response, rectification ratio, barrier height and ideality factor were performed between the two synthesized CuS NPs based devices. Under no light condition, the rectification ratio for CuS(solv) increased by 28 % more than that of CuS(co-pr). The photo response for CuS(solv) also enhanced by 146 %. For a better understanding of junction and carrier transport properties space charge limited current (SCLC) theory is incorporated. The interfacial resistance of the devices was studied by Nyquist plots obtained from the impedance spectroscopy and were also fitted by equivalent circuit model and explained the mechanism of charge transport through the Schottky interface. The transit time and carrier mobility were improved for CuS(solv) than CuS(co-pr). Thus, the solvothermally synthesized CuS-based device could be assigned as it possesses lesser number of lattice defects, better crystallinity and larger particle size along with its better film properties leading to better performance. [Display omitted] • Optical absorption edge of CuS(solv) shifted towards the longer wavelength than CuS(co-pr). • CuS NPs synthesized by solvothermal method exhibits improved charge transport and photo response over CuS(co-precipitation). • Fewer carrier recombination through M−S junction make CuS(solv) a better Schottky device over CuS(co-pr). • Lesser lattice defects and better thin film properties enhances performance of CuS(solv) based Schottky diode. [ABSTRACT FROM AUTHOR]