Zinc oxide, an n-type, II–IV semiconductor, is a commercially important material used in solar cells [1], rubber [2], sensors [3], varistors [4], etc.
Also it is a self-activated crystal of a hexagonal wurtzite structure with direct band gap energy 3.37 eV and relatively high exciton binding energy (60 meV) at room temperature [5], displays excellent piezoelectric [6], catalysis [7] and novel optical properties [8].