Abstract:

Organic-inorganic hybrid perovskite methylammonium lead iodide (CH₃NH₃PbI₃) generally tends to show n-type semiconductor properties. In this work, a field-effect transistor (FET) device based on a CH₃NH₃PbI₃ single crystal with tantalum pentoxide (Ta₂O₅) as the top gate dielectric was fabricated. The p-type field-effect transport properties of the device were observed in the dark. The hole mobility of the device extracted from transfer characteristics in the dark was 8.7×10^-5 cm²·V^-1·s^-1, which is one order of magnitude higher than that of polycrystalline FETs with SiO₂ as the bottom gate dielectric. In addition, the effect of light illumination on the CH₃NH₃PbI₃ single-crystal FET was studied. Light illumination strongly influenced the field effect of the device because of the intense photoelectric response of the CH₃NH₃PbI₃ single crystal. Different from a CH₃NH₃PbI₃ polycrystalline FET with a bottom gate dielectric, even with the top gate dielectric shielding, light illumination of 5.00 mW·cm^-2 caused the hole current to increase by one order of magnitude compared with that in the dark (V_GS (gate-source voltage)=V_DS (drain-source voltage)=20 V) and the photoresponsivity reached 2.5 A·W^-1. The introduction of Ta₂O₅ as the top gate dielectric selectively enhanced hole transport in the single-crystal FET, indicating that in the absence of external factors, by appropriate device design, CH₃NH₃PbI₃ also has potential for use in ambipolar transistors.

Key words: Perovskite, Tantalum pentoxide, Field-effect, Mobility, Light illumination