This book presents a clear and comprehensive coverage of the synthesis and characterization techniques of pure prepared semiconductor ZnO, doped ZnO and Modified ZnO nanoparticles which have potential applications in optoelectronics devices. Salient features involves: Synthesis and structural,optical characterization of pure and doped (Cu and Sb) ZnO nanoparticles. Synthesis and structural, optical characterization of modified ZnO nanoparticles using 2-aminothiols and 2-aminothiophenol as the capping agent for surface modification of ZnO nanoparticles. Possible optoelectronics application has been discussed by using modified ZnO nanoparticles for the realization of molecular AND gate.