Low‐Temperature Atomic Layer Deposition of High‐<i>k</i> SbO<i><sub>x</sub></i> for Thin Film Transistors
Jun Yang, Amin Bahrami, Xingwei Ding, Panpan Zhao, Shiyang He, Sebastian Lehmann, Mikko Laitinen, Jaakko Julin, Mikko Kivekäs, Timo Sajavaara, Kornelius Nielsch
Abstract
Abstract SbO x thin films are deposited by atomic layer deposition (ALD) using SbCl 5 and Sb(NMe 2 ) 3 as antimony reactants and H 2 O and H 2 O 2 as oxidizers at low temperatures. SbCl5 can react with both oxidizers, while no deposition is found to occur using Sb(NMe 2 ) 3 and H 2 O. For the first time, the reaction mechanism and dielectric properties of ALD‐SbO x thin films are systematically studied, which exhibit a high breakdown field of ≈4 MV cm −1 and high areal capacitance ranging from 150 to 200 nF cm −2 , corresponding to a dielectric constant ranging from 10 to 13. The ZnO semiconductor layer is integrated into a SbO x dielectric layer, and thin film transistors (TFTs) are successfully fabricated. A TFT with a SbO x dielectric layer deposited at 200 °C from Sb(NMe 2 ) 3 and H 2 O 2 presents excellent performance, such as a field effect mobility ( µ ) of 12.4 cm 2 V −1 s −1 , I on / I off ratio of 4 × 10 8 , subthreshold swing of 0.22 V dec −1 , and a trapping state ( N trap ) of 1.1 × 10 12 eV −1 cm −2 . The amorphous structure and high areal capacitance of SbO x boosts the interface between the semiconductor and dielectric layer of TFT devices and provide a strong electric field for electrons to improve the device mobility.