Boron induced c-axis growth and ammonia sensing signatures of spray pyrolysis deposited ZnO thin films – Relation between crystallinity and sensing

•Optimization of spray deposition parameters for c-axis oriented B-doped ZnO thin films.•Substitution of B in ZnO lattice developed a tensile stress in c-axis.•10 mol% of B-doped ZnO showed ammonia sensing response at room temperature.•Confirmation of link between crystal plane orientation and ammonia sensing performance. Boron (B) doping in zinc oxide (ZnO) using spray pyrolysis has always led to deterioration of host crystal structure. Unlikely, here, we report the optimized spray pyrolysis deposition parameters for the development of c-axis oriented boron-doped ZnO thin films. As the B concentration increases from 2 to 10 mol%, the hexagonal crystal structure exhibited a highly oriented (002) plane with an increased texture co-efficient. In particular, 2 mol% B dopants promoted the growth of the (101) and (100) planes and increased the crystallite size. Tensile stress in the c-axis plane of 10 mol% B-doped ZnO films leads to the red shift in the band gap (from wide to narrow). Furthermore, 10 mol% B dopants resulted in the enhanced ammonia sensing performance at room temperature. The sensing performance of all the deposited B-doped ZnO films revealed that influence of enhanced planes of host structure energetically favoured the ammonia adsorption.