Interfacial structure and electrical characteristics of LaNiO₃/Si contacts

Abstract

The LaNiO₃ (LNO) thin films were deposited on Si substrate by rf magnetron sputtering. The interface and electrical properties of LNO/Si contacts were investigated. For the deposition at room temperature, an amorphous LNO film with a clean interface was formed on the Si. However, a thin silicon oxide layer of approximately 2.5 nm was formed at the interface between LNO and Si after rapid thermal annealing (RTA) at temperatures ≥450 °C. On the other hand, a highly (100)-textured LNO film along with an interfacial oxide layer of approximately 6.0 nm was obtained for the deposition at 400–450 °C. Nevertheless, if an ion beam etching was applied prior to the high temperature deposition at 400–450 °C, a clean interface at the interface could be obtained for the LNO/Si contacts. Moreover, crystallites with (111) planes grown epitaxially along the (111) planes of Si were found in the LNO films. All the contacts had shown good current–voltage characteristics of a Schottky diode with a barrier height of 0.69–0.78 eV for the LNO/n-Si contacts and 0.60–0.67 eV for the LNO/p-Si contacts, and the barrier height increased with the thickening of interfacial oxide layer. From the measurement of capacitance (C) under reverse bias (V_r) of the contacts made with LNO deposited on the ion-etched Si substrates, a linear relation was observed in the plot of C ⁻² against V_r except a deviation of linearity in the low-bias part of the curve. This deviation is most likely due to the segregation and inward diffusion of La and Ni near the interface of LNO/Si contacts. Nevertheless, the barrier heights evaluated from an extrapolation of linear part of the plots are reasonably consistent with those obtained from the I–V measurement.