Phosphorene field-effect transistors using high-k gate dielectrics of epitaxial SrTiO3 layers grown on Nb-doped SrTiO3 substrates

Epitaxial SrTiO3 (STO) thin film as a gate dielectric layer was grown on single crystalline (100) Nb-doped SrTiO3 substrate. On the 100-nm-thick STO gate dielectric layer, a 5-nm-thick phosphorene sheet channel layer was exfoliated from a bulk crystal. A phosphorene field-effect transistor (P-STO-FET) was prepared by the formation of 90-nm-thick Au source/drain (S/D) contacts. The P-STO-FET exhibited the transport characteristics of a p-type transistor with a mobility of approximately 376 cm−2/Vs and an on/off ratio of approximately 103. Furthermore, it was experimentally confirmed that the mobility of the P-STO-FET was significantly influenced by the flatness of the phosphorene sheet.