Preparation and performance optimization of HfAlO hybrid gate dielectric thin films driven by solution

The drawbacks of binary metal oxide gate media are gradually emerging, and research on ternary and even multivariate metal oxides is gradually increasing. HfAlO gate dielectric films with different aluminum contents were prepared using the solution method. When Hf: Al = 2:1, the HfAlO film exhibits excellent optical properties with a larger E_g (~5.80 eV) and maximum ∆E_C (~2.22 eV). Through XPS analysis, HAO-2 has a relatively high proportion of M–O bonds (69.03%), the lowest proportion of oxygen vacancies (16.16%), and a relatively low proportion of bonded oxygen (14.81%). MOS capacitors with Al/HAO-2/p-Si/Al structure exhibit excellent performance, high k value (9.63), and minimum defect density and leakage current density. In the analysis of the leakage current mechanism, almost all samples exhibit a leakage current conduction mechanism under substrate injection, which follows the pattern of Schottky emission as the primary source at low field strengths, Pool–Frenkel emission as the primary source at high field strengths, and direct tunneling as the primary source at high field strengths.