Electronic excitation induced effects on the structural and electrical properties of HfO2 thin films

Abstract

newlineIn this thesis, the effects of electronic excitation induced by Gamma irradiation, Swift Heavy Ion newline(SHI) irradiation and Laser annealing on the structural and electrical properties of HfO2 thin films newlinehave been studied. Further, an array of high density gold nanoparticles have been produced on the newlinesurface of HfO2 thin films, without modifying the phase of HfO2 using a non-thermal laser newlineannealing technique. HfO2 thin films used in this study were deposited on high mobility and/or newlinewide bandgap semiconductor substrates by using Radio Frequency (RF) magnetron sputtering and newlinee-beam evaporation techniques. newlineAs expected, thermal annealing has introduced monoclinic phase in otherwise amorphous HfO2 newlinethin films which resulted in an increase in the leakage current density of the HfO2 based Metal newlineOxide Semiconductor (MOS) structures. A systematic increase in leakage current density indicates newlinethe production of defects in HfO2 thin films with increasing gamma irradiation dose. SHI (120 newlineMeV Ag) irradiation resulted in a systematic increase in the grain size and increase in the newlineroughness of the HfO2 films. As-grown HfO2 thin films are amorphous in nature. Ion induced newlinephase transformation of HfO2 thin films from amorphous to monoclinic and tetragonal phases have newlinebeen observed. The influence of Poole-Frenkel (PF) and Fowler-Nordheim (FN) tunneling newlineprocesses have been investigated by examining the Leakage current-Voltage (I-V) characteristics. newlineThe tunneling mechanisms revealed the existence of defects in the as-grown HfO2 films. Ion newlineinduced defect annealing has been observed below the critical fluence (5x1012 ions/cm2) which newlineresulted in decrease of the leakage current density. Whereas ion induced defect creation and newlineradiation damage have been observed above the critical fluence, which resulted in an increase in newlinethe leakage current density. Further, an array of high density gold nanoparticles has been produced newlineon the surface of HfO2 thin films without modifying the phase of HfO2 by subjecting the Au/HfO2 newlinebi-layers to lase