We report investigations of ZnO plasma at various ambient pressures of oxygen produced by third harmonic 355 nm of neodymium: yttrium aluminum garnet laser for depositing quality nanocrystalline ZnO thin films. Time- and space-resolved optical emission spectroscopy is used to correlate the plasma properties with that of the deposited thin films. The temporally resolved images of the plumes are correlated with the time-resolved emission spectrum of plasma species in the plume. The deposited films of ZnO at 100 mTorr of ambient oxygen exhibited third-harmonic generation. Mgx Zn(1-x) O alloy thin films of different molar percentage of MgO were deposited on glass substrates with the aim of achieving variable band gap using pulsed laser deposition in 100-mTorr oxygen ambient at substrate temperatures ranging from 200 to 500 °C. The films with x=0.1 and 0.3 exhibit single hexagonal phase with (002) as the preferred orientation, however, with x=0.5, a transition to mixed phase with hexagonal phase of (100) and cubic phase of (200) orientation is observed. The absorption edge is blueshifted with and increase of x and deposition temperature. The band gap of the deposited films increases with molar percentage and deposition temperature. The deposited films exhibited high degree of transparency (>85%) over visible range. © 2005 American Institute of Physics.