All-in-One Optoelectronic Logic Gates Enabled by Bipolar Spectral Photoresponse of CdTe/SnSe Heterojunction

Abstract

Optoelectronic logic gate devices (OLGDs) have attracted significant attention in high-density information processors; however, multifunctional logic operation in a single device is technically challenging due to the unidirectional electrical transport. In this work, we deliberately design all-in-one OLGDs based on self-powered CdTe/SnSe heterojunction photodetectors. The SnSe nanorod (NR) array is grown on the sputtered CdTe film via a glancing-angle deposition technique to form a heterojunction device. At the interface, the photovoltaic (PV) effect in the CdTe/SnSe heterojunction and the photothermoelectric (PTE) effect from the SnSe NRs are combined together to induce the reversed photocurrent, leading to a unique bipolar spectral response. The competition between PV and PTE in different spectral ranges is thus employed to control the photocurrent polarity, and five basic logic gates of OR, AND, NAND, NOR, and NOT can be performed just with a single heterojunction. Our findings indicate the large potentials of the CdTe/SnSe heterojunctions as logic units in next-generation sensing-computing systems.

Self-Powered FTO/CdSe/Bi2Se3 Photodetector with Bipolar Photoresponse Characteristics

“…With the continuous advancement of information technology, the demand for photoelectric detection is rapidly increasing. − To meet the needs of different application fields, photodetectors based on different structures such as positive-negative (PN), positive-intrinsic-negative (PIN), and metal-semiconductor (MS) junctions have been constructed. Most photodetectors can only produce unidirectional photoelectric signals for specific wavelengths of light, limiting their versatility. − Bipolar photoresponse detectors offer advantages in terms of integration and multifunctionality due to their bipolar output capability and hold promise for applications in biosensors, optical logic gates, and artificial synapse simulation. − …”

“…To date, various mechanisms have been introduced regarding the design of bipolar photoresponse devices, such as the photovoltaic (PV) effect, photothermoelectric (PTE) effect, and photoelectrochemical (PEC) effect. − Most of the motivation of the reported works is to utilize competition between different mechanisms in different spectral ranges to control the photocurrent polarity. For instance, Liu et al achieved a bipolar response based on the competition between the PV effect in the CdTe/SnSe heterojunction and the PTE effect from the SnSe NRs to generate the bipolar photocurrent. In this case, one must pay special attention to the band alignment and Seebeck coefficient matching and carefully control the wavelength of incident light to tune the photocurrent polarity, which limit the flexibility of choosing semiconductor materials.…”