Strain-induced modulation on phonon and electronic properties of suspended black phosphorus field effect transistor

Black phosphorus has recently appeared as a promising two-dimensional material for applications in high performance nanoelectronics. Its single- and few-atomic layer forms in field-effect transistors have attracted a lot of attention due to the tunable bandgap (0.3-2.0 eV), high carrier mobility (1000 cm2 V−1 s−1) and decent on-off ratios (105). Here, we demonstrate a suspended black phosphorus field effect transistor (BP-FET) and utilize Raman spectroscope to characterize the strain on the effects of Raman phonon. We find that red shifts appear in all the three vibrational modes (Ag1, B2g and Ag2) in different degrees. Among them, Ag1 mode is most sensitive to the tensile strain. We further investigate the electronic properties with a Cascade semi-automatic probe station. The linear relationships in the output curves indicate the contacts between black phosphorus and electrodes are ohmic contacts. The transfer characteristic curves declare the drain current modulation is ∼7.6×103 for the hole conduction and ∼57 for the electron conduction. Mobility of this device is found to be 347.5 cm2 V−1 s−1 and 4.9 cm2 V−1 s−1 for the hole and electron conduction, respectively. These results provide a theoretical basis for the coordination of high-performance black phosphorus electronic components.