Antiambipolar and Bidirectional Photoresponse in Ternary van der Waals Heterostructure Transistors

Next-generation nanoelectronics require device architectures that integrate high density, multifunctionality, and low power consumption. Antiambipolar transistors (AATs) are promising candidates for multivalued logic and intelligent sensing, yet conventional two-dimensional (2D) AATs suffer from low peak-to-valley current ratios (PVRs) and unidirectional self-driven photoresponse. Here, we report a multifunctional AAT based on a MoS2/Ta2NiS5/MoTe2 double van der Waals heterostructure (vdWH). The device exhibits outstanding antiambipolar transport characteristics, achieving an ultrahigh PVR of 1 × 107 and a peak current of 1.2 μA, surpassing those of most previously reported 2D AATs. By introducing Ta2NiS5 as an intermediate layer, a back-to-back type-I band alignment is established, enabling efficient modulation and reversal of interfacial band bending under different bias conditions. Simultaneously, under 635 nm illumination, the device exhibits a gate-tunable bidirectional photocurrent response, with responsivities of +2.94 and −0.65 A/W at Vgs = +40 and −40 V, respectively. Furthermore, the device is demonstrated in ternary logic inverters, in-sensor image convolution processing, and multimodal information encoding. These results demonstrate the potential of van der Waals heterostructure-based antiambipolar transistors for integrated and reconfigurable optoelectronic systems.