Low-Temperature Dielectric Response of Strontium Titanate Thin Films Manipulated by Zn Doping

The voltage dependence of the dielectric permittivity ε' and the low dielectric loss tanδ of incipient ferroelectrics have drawn vast attention to the use of these materials for the development of tuning elements in electronics and telecommunications. Here, we study the DC electric field dependence of low-temperature ε' in ~320 nm thick sol-gel-derived SrTi_1-xZn_xO_3-δ thin films with x = 0.01 and 0.05, deposited on Pt/TiO₂/SiO₂/Si substrates. Incorporation of Zn onto Ti sites is found to decrease ε' compared to undoped SrTiO₃ films, while increasing the relative tunability n up to ~32.9% under a DC electric field of 125 kV/cm at low temperatures. The hysteresis-free variation in ε' with electric field and tanδ values below 0.6% observed for SrTi_1-xZn_xO_3-δ film with x = 0.01 make this compound more attractive for tunable device applications.