Effect of silver doping on electrical characteristics of aluminum/HfO2/p-silicon metal-oxide-semiconductor devices

In this study, undoped and silver (Ag) doped hafnium oxide (HfO2) thin films were prepared by sol-gel dipping method and their effect as an interface material in a p-Si-based metal-oxide-semiconductor device was investigated for the first time. The structural effects of Ag doping were investigated using x-ray diffraction patterns. Al/HfO2:Ag/p-Si devices were fabricated using these films, and their electrical properties were characterized by measuring current-voltage (I-V) curves at room temperature. The ideality factor values of the devices decreased from 4.09 to 2.20 as the Ag doping ratio increased. Simultaneously, the barrier height values increased from 0.60 eV to 0.81 eV. The calculated series resistance values, determined by two different methods, demonstrated that the lowest resistance values were obtained at a 1% Ag doping ratio. Furthermore, the interface state densities were found to vary with the doping ratio. The improvement in electrical parameters resulting from Ag doping can be attributed to the reduction in molar volume due to structural phase transformation. The decrease in the ideality factor suggests enhanced carrier transport efficiency, while the increase in barrier height indicates improved energy band alignment at the metal/semiconductor interface.