Fabrication of strontium included hafnium oxide thin film based Al/Sr:HfO2/n-Si MIS-Schottky barrier diodes for tuned electrical behavior

Abstract

The growth behavior of pure and Sr included HfO₂ composite thin films for different concentrations of Sr (5, 10, and 15 Wt%) through the Jet Nebulizer Spray Pyrolysis technique is discussed in detail. The preparation of Al/HfO₂/n-Si and Al/Sr:HfO₂/n-Si Schottky barrier diodes and their rectification behavior were compared. The appearance of intermediate (Sr₂HfO₄) and new (SrO₂) phases upon introduction of Sr in HfO₂ was recorded through XRD analysis, and particle size enlargement was observed. The absorption coefficients and bandgap energies of pure and Sr included HfO₂ films were determined using UV-VIS analysis, and the results imply that the presence of Sr₂HfO₄ in Sr:HfO₂ increases the overall bandgap from 3.8 to 4.0 eV. The morphology of pure HfO₂ was heavily influenced by the presence of Sr; FESEM micrographs revealed that the self-assembled sphere like structure of HfO₂ turned into mixed morphology like the rod shape of SrO₂ and the contorted spheres of Sr₂HfO₄. EDAX elementary studies have confirmed the presence and percentage changes of Sr, Hf, and O in pure and Sr included composites thin films. The XPS spectrum has confirmed Sr in SrO₂ and Sr₂HfO₄ phases, and its oxidation states in different phases were verified using short XPS scans. The I–V curves of pure (Al/HfO₂/n-Si) and Sr:HfO₂ composite (Al/Sr–HfO₂/n-Si) diodes were studied and compared. The 15% Sr included HfO₂ showed higher rectification behavior when compared with pure Al/HfO₂/n-Si and composited (5 and 10%) Al/Sr–HfO₂/n-Si at room temperature.