Reconfigurable Phototransistors\nDriven by Gate-Dependent\nCarrier Modulation in WSe<sub>2</sub>/Ta<sub>2</sub>NiSe<sub>5</sub> van der Waals Heterojunctions

Reconfigurable field-effect transistors (RFETs) offer\nnotable benefits\non electronic and optoelectronic logic circuits, surpassing the integration,\nflexibility, and cost-efficiency of conventional complementary metal-oxide\nsemiconductor transistors. The low on/off current ratio of these transistors\nremains a considerable impediment in the practical application of\nRFETs. To overcome these limitations, a van der Waals heterojunction\n(vdWH) transistor composed of WSe<sub>2</sub>/Ta<sub>2</sub>NiSe<sub>5</sub> has been proposed. By modulating a single back-gate voltage\nand source-drain voltage inputs, the transistor achieves a switchable\npolarity configuration and bidirectional rectification, making it\ncapable of functioning as a gate-controlled bidirectional half-wave\nrectifier. The proposed RFET exhibits tunable positive/negative photovoltaic\nresponses, advanced optoelectronic performance, and a gate-voltage-dependent\nreversal of the photodetector position. Detailed energy band diagram\nstudies have shown that the reconfigurability of the device arises\nfrom carrier blockage resulting from the type-I band structure and\ncarrier injection modulated by gate-dependent Schottky barriers. Consequently,\nthe reconfigurable WSe<sub>2</sub>/Ta<sub>2</sub>NiSe<sub>5</sub> vdWH\nholds significant promise for advanced multifunctional optoelectronic\ndevice applications.