Wang W.,Hebei University of Technology |
Wang W.,Key Laboratory of Electronic Materials and Devices of Tianjin |
Shi X.,Hebei University of Technology |
Shi X.,Key Laboratory of Electronic Materials and Devices of Tianjin |
And 4 more authors.
IEEE Electron Device Letters | Year: 2016
Ta2O5 films of 200 nm thick with and without octadecyltrichlorosilane (OTS) surface modification were prepared and used as gate dielectrics to fabricate pentacene metal-insulator-semiconductor (MIS) capacitors. The dielectric constants of Ta2O5 film and OTS-treated Ta2O5 film were determined to be 20.6 and 19.3 at 1 MHz, and both the films exhibit good permittivity stability and low leakage characteristics with the bias voltage sweeping from -10 to 10 V. Atomic force microscopy and Hall measurements show that a pentacene polycrystalline film deposited on OTS-treated Ta2O5 has a high grain packing density with an improved grain contact, and thus a high hole mobility of 3.5 cm2/Vs. Capacitance-voltage and conductance-voltage analysis of pentacene MIS capacitors demonstrate that OTS modification induces a positive shift of flatband voltage from 3.1 to 3.8 V, and effectively minimizes the interface state density of pentacene/dielectric from 5.1× 1012 cm-2 eV-1 to 9.6× 1010 cm-2 eV-1. The results indicate that high-k Ta2O5 film with OTS modification would be a promising gate dielectric for pentacene thin-film transistors in low-end electronics. © 2016 IEEE.