[19a-Z14-1~11] 6.3 Oxide electronics

▼ [19a-Z14-11] Electrical gate control of the two-dimensional carrier gas at the FeO_y/SrTiO₃ interface

〇(B)Theodorus Jonathan Wijaya¹, Le Duc Anh^1,2,3, Shingo Kaneta-Takada¹, Masaaki Tanaka^1,4, Shinobu Ohya^1,2,4 (1.Dept. of EEIS, The Univ. of Tokyo, 2.IEI, The Univ. of Tokyo, 3.PRESTO, JST, 4.CSRN, The Univ. of Tokyo)

Keywords:Perovskite oxides, 2D carrier gas, Electrical gate control

In our previous work, by depositing a sub-nm Fe layer on SrTiO₃ (STO) substrates, we demonstrated the realization of both two-dimensional (2D) hole and electron gas with ultrahigh mobilities up to 24000 cm²/Vs, whose carrier type can be controlled by the Fe thickness [L. D. Anh et al., Adv. Mater. 32, 1906003 (2020)]. This discovery potentially provides a universal platform for oxide-based electronics. Here, using a back-gate configuration, we demonstrate that the carrier type and mobility of these 2D carrier gases can be effectively controlled by gate voltage (V_G). The samples were made by depositing Al (1 nm)/Fe (0.075–0.4 nm) on STO substrates using molecular beam epitaxy. In all samples, the carrier type is changed from n- to p-type when V_G is swept from -12 to 25 V, where the threshold gate voltage of the carrier-type switching varies by samples. These results provide insights into the complicated band structure and the formation mechanism of 2DHG at the FeO_y/SrTiO₃ interfaces.