A detailed study on frequency dependent electrical characteristics of MOS capacitors with dysprosium oxide gate dielectrics

Abstract

Frequency dependent electrical characteristics of Al/Dy2O3/p-Si/Ag MOS capacitors have been systematically investigated incorporating interfacial chemical structures of the capacitors to specify where interface state signals arise from. The results show that capacitance (C) increases with decreasing in the applied voltage frequency due to the response time dependency of the interface states. Conductance (G) curves have a single peak at the relatively high frequencies as expected. Interestingly, the G curves exhibit two distinct peaks at 400 kHz and lower frequencies. These G peaks are associated with acceptor-like interface (Dit,ac) and donor-like interface (Dit,dn) states. Electrochemical analysis has also depicted that non-stoichiometric DySiOx and SiOx bonds are present at the interface between Dy2O3/Si gate stack. Owing to interactions between mobile charge carriers and possible defect sites present at the DySiOx and SiOx, the Dit,ac and Dit,dn signals have been observed at G curves. In addition, the C hysteresis loop widths decrease with decreasing in the voltage frequencies due to opposite polarity and response time dependencies of the Dit,ac and Dit,dn states. The oxide, interface and border trap densities of capacitors exhibit slight frequency variations and their orders are comparable with device used in the state of the art microelectronics technologies. On the other hand, barrier potential varies from 0.97 eV to 1.136 eV depending on the voltage frequencies. Leakage current density was found to be 1.61 × 10−7 Acm−2 at −1 V and Fowler–Nordheim tunneling mechanism dominates the leakage current conduction. Considering to these results, it can be concluded that the Dy2O3 shows promising dielectric and insulating behavior for the application in future microelectronics technology.