A field-effect WSe_(2)/Si heterojunction diode

It is significant to develop a heterogeneous integration technology to promote the application of two-dimensional(2D)materials in silicon roadmap. In this paper, we reported a field-effect WSe_(2)/Si heterojunction diode based on ambipolar 2D WSe_(2) and silicon on insulator(SOI). Our results indicate that the device exhibits a p–n diode behavior with a rectifying ratio of ~300 and an ideality factor of 1.37. As a photodetector, it has optoelectronic properties with a response time of 0.13 ms, responsivity of 0.045 A/W, detectivity of 4.5×10~(10) Jones and external quantum efficiency(EQE) of 8.9 %.Due to the ambipolar behavior of the WSe_(2), the rectifying and optoelectronic properties of the heterojunction diode can be modulated by the gate electrical field, enabling various potential applications such as logic optoelectronic devices and neuromorphic optoelectronic devices for in-sensor computing circuits. Thanks to the process based on the mature SOI technique, our field-effect heterojunction diode should have obvious advantages in device isolation and integration.

Two-dimensional complementary gate-programmable PN junctions for reconfigurable rectifier circuit

The unique features of ambipolar two-dimensional materials open up a great opportunity to build gate-programmable devices for reconfigurable circuit applications,e.g.,PN junctions for rectifier circuits.However,current-reported rectifier circuits usually consist of one gate-programmable PN junction as the rectifier and one resistor as the load,which are not conductive to voltage output and large-scale integration.Here we propose an approach of complementary gate-programmable PN junctions to assemble reconfigurable rectifier circuit,which include two symmetric back-to-back black phosphorus(BP)/hexagonal boron nitride(h-BN)/graphene heterostructured semi-gate field-effect transistors(FETs)and perform complementary NP and PN junction like complementary metal-oxide-semiconductor(CMOS)circuit.The investigation exhibits that the circuit can effectively reconfigure the circuit with/without rectifying ability,and can process alternating current(AC)signals with the frequency prior 1 KHz and reconfiguration speed up to 25μs.We also achieve the reconfigurable rectifier circuit memory via complementary semi-floating gate FETs configuration.The complementary configuration here should be of low output impedance and low static power consumption,being beneficial for effective voltage output and large-scale integration.

Van der Waals contacted WSe_(2) ambipolar transistor for in-sensor computing

Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode arrays.It demands the composed photodiodes are reconfigurable,which are usually achieved by ambipolar two-dimensional(2D)semiconductors.To improve the ambipolar charges injection,here we report a top-gated field-effect transistor(FET)design that is of bottom van der Waals contact via transferring ambipolar 2D WSe_(2) onto Pd/Cr source/drain electrodes.The devices exhibit nearly negligible effective barrier heights for both holes and electrons based on thermionic emission mode,and show an almost balanced on/off ratio in the p-branch and n-branch.By replacing the top gate with two aligned semi-gates,the devices can effectively function as reconfigurable photodiodes.They can be switched between PIN and NIP configurations via controlling the two semi-gates,exhibiting good linearity in terms of short-circuit current(ISC)and incident light power density.The photodiode arrays are also demonstrated for in-sensor optoelectronic convolutional image processing,showing significant potential for in-sensor computing image processors.