Trion Engineered Multimodal Transistors in Two dimensional Bilayer Semiconductor Lateral Heterostructures

TL;DR

This study demonstrates how bilayer 2D lateral heterostructures can be engineered to control exciton and trion dynamics for advanced multimodal optoelectronic applications, without external confinement.

Contribution

It introduces a novel approach using bilayer 2D lateral npn heterostructures for intrinsic exciton engineering and multimodal device operation, expanding beyond traditional vertical heterostructures.

Findings

Dynamic tuning of channel photoresponsivity from positive to negative.

Observation of trions and intrinsic trap states in bilayer MoSe2 and WSe2.

Multifunctional phototransistors enabling electrical and optical control of excitonic properties.

Abstract

Multimodal device operations are essential to advancing the integration of 2D semiconductors in electronics, photonics, information and quantum technology. Precise control over carrier dynamics, particularly exciton generation and transport, is crucial for finetuning the functionality of optoelectronic devices based on 2D semiconductor heterostructure. However, the traditional exciton engineering methods in 2D semiconductors are mainly restricted to the artificially assembled vertical pn heterostructures with electrical or strain induced confinements. In this study, we utilized bilayer 2D lateral npn multijunction heterostructures with intrinsically spatially separated energy landscapes to achieve preferential exciton generation and manipulation without external confinement. In lateral npn FET geometry, we uncover unique and nontrivial properties, including dynamic tuning of channel photoresponsivity from positive to negative. The multimodal operation of these 2D FETs is achieved by carefully adjusting electrical bias and the impinging photon energy, enabling precise control over the trions generation and transport. Cryogenic photoluminescence measurement revealed the presence of trions in bilayer MoSe2 and intrinsic trap states in WSe2. Measurements in different FET device geometries show the multifunctionality of 2D lateral heterostructure phototransistors for efficient tuning and electrical manipulation of excitonic characteristics. Our findings pave the way for developing practical exciton-based transistors, sensors, multimodal optoelectronic and quantum technologies