Electrical and dielectric characteristics of Al/Dy2O3/p-Si heterostructure

In this work we report the electrical characteristics of high-k Dy2O3 dielectric deposited on p-Si substrate by electron beam deposition under ultra vacuum. The surface morphology of Dy2O3 is investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface topography analysis reveals that the Dy2O3 film is nanograined and contains numerous contacts between columnar grains. The electrical properties of Al/Dy2O3/p-Si heterostructure are further analyzed by current–voltage (I–V), capacitance–voltage (C–V), capacitance–frequency (C–f) and conductance–frequency (G–f) measurements. The dominant conduction mechanisms which governed the Al/Dy2O3/p-Si heterostrucure are determined. The hetrostructure induces a significant value of leakage current: 1.1×10−5 A at flat-band voltage −1 V which is linked to the structural properties of the elaborated structure. The effects of grain boundaries and oxygen vacancies within the dielectric are observed in term of leakage current. Indeed, the C(V) characteristics measured at different applied voltage show a large frequency–dispersion, indicative of the presence of a continuous distribution of interface states. So, the interface state densities are determined from the C(V) characteristics to be around 1013 eV−1 cm−2. C(f) measurements elucidate that the capacitance behavior is typical of material with traps. From G(f) and C(f) measurement the trap density and relaxation time are also determined. It is suggested that the interface states series resistance are important parameters that strongly influence the electrical properties of Al/Dy2O3/p-Si heterostrucure.