Oxide Semiconductor Heterojunction Transistor with Negative Differential Transconductance for Multivalued Logic Circuits

Abstract

Multivalued logic (MVL) technology is a promising solution for improving data density and reducing power consumption in comparison to complementary metal-oxide-semiconductor (CMOS) technology. Currently, heterojunction transistors (TRs) with negative differential transconductance (NDT) characteristics, which play an important role in the function of MVL circuits, adopt organic or 2D semiconductors as active layers, but it is still difficult to apply conventional CMOS processes. Herein, we demonstrate an oxide semiconductor (OS) heterojunction TR with NDT characteristics composed of p-type copper(I) oxide (Cu 2 O) and n-type indium gallium zinc oxide (IGZO) using the conventional CMOS manufacturing processes. The electrical characteristics of the fabricated device exhibit a high I on /I off ratio (∼3 × 10 3 ), wide NDT ranges (∼29 V), and high peakto-valley current ratios (PVCR ≈ 25). The electrical properties of 15 devices were measured, confirming uniform performance in the PVCR, NDT range, and I on /I off ratio. We analyze the device operation by varying the source/drain (S/D) position and changing the device geometry and the thickness of the Cu 2 O layer. Additionally, we demonstrate heterojunction ambipolar TR to elucidate the transport mechanism of NDT devices at a high gate voltage (V GS ). To confirm the feasibility of the MVL circuit, we present a ternary inverter with three clearly expressed logic states that have a long intermediate state and greater margin of error induced by wide NDT regions and high PVCR.

Highly Sensitive Diethylamine Detection at Room Temperature Using g-C3N4 Nanosheets Decorated with CuO Hollow Polyhedral Structures

“…The difference in Fermi levels between n-type g-C 3 N 4 (2.7 eV) and p-type CuO (1.2 eV) causes electrons to migrate from the conduction band of g-C 3 N 4 to the CuO band, while holes move from CuO to g-C 3 N 4 until their Fermi levels equalize at the interface. ,− The energy band near the interface experiences significant bending due to numerous electron transitions . The interaction between CuO and g-C 3 N 4 results in electron neutralization of holes in the HAL on CuO, forming a hole depletion layer on the CuO side, reducing the thickness of the HAL on g-C 3 N 4 -CuO HPHSs due to the exchange of electrons and holes (Figure d). , The g-C 3 N 4 -CuO HPHS sensor has better gas sensitivity than pure CuO due to the lattice mismatch between CuO and g-C 3 N 4 . This mismatch causes defects around the p-n junction, which may facilitate gas adsorption and surface reactions, increasing the potential for surface interactions between DEA molecules and oxygen ions.…”

“…The g-C 3 N 4 nanosheets significantly improve the gas-sensing performance in g-C 3 N 4 -CuO HPHSs, as the formation of p-n heterojunctions between the two materials enhances their properties. The difference in Fermi levels between n-type g-C 3 N 4 (2.7 eV) and p-type CuO (1.2 eV) causes electrons to migrate from the conduction band of g-C 3 N 4 to the CuO band, while holes move from CuO to g-C 3 N 4 until their Fermi levels equalize at the interface. ,− The energy band near the interface experiences significant bending due to numerous electron transitions . The interaction between CuO and g-C 3 N 4 results in electron neutralization of holes in the HAL on CuO, forming a hole depletion layer on the CuO side, reducing the thickness of the HAL on g-C 3 N 4 -CuO HPHSs due to the exchange of electrons and holes (Figure d). , The g-C 3 N 4 -CuO HPHS sensor has better gas sensitivity than pure CuO due to the lattice mismatch between CuO and g-C 3 N 4 .…”