Abstract

Multimodal device operations are essential to advancing the on-chip integration of two-dimensional (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 p-n heterostructures with electrical or strain-induced confinements. In this study, we utilized bilayer 2D lateral n-p-n multi-junction MoSe₂-WSe₂-MoSe₂ heterostructures with intrinsically spatially separated energy landscapes to achieve preferential exciton generation and manipulation without the need for external confinement. In lateral n-p-n field-effect transistor (FET) geometry, we uncover unique and non-trivial electro-optical 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, which enhanced the sensitivity of the proposed device to near-infrared photons. Measurements in different FET device geometries show the multi-functionality 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 on-chip and quantum technologies.

Abstract

Multimodal device operations are essential to advancing the on-chip integration of two-dimensional (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 p-n heterostructures with electrical or strain-induced confinements. In this study, we utilized bilayer 2D lateral n-p-n multi-junction MoSe₂-WSe₂-MoSe₂ heterostructures with intrinsically spatially separated energy landscapes to achieve preferential exciton generation and manipulation without the need for external confinement. In lateral n-p-n field-effect transistor (FET) geometry, we uncover unique and non-trivial electro-optical 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, which enhanced the sensitivity of the proposed device to near-infrared photons. Measurements in different FET device geometries show the multi-functionality 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 on-chip and quantum technologies.

Abstract

Multimodal device operations are essential to advancing the on-chip integration of two-dimensional (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 p-n heterostructures with electrical or strain-induced confinements. In this study, we utilized bilayer 2D lateral n-p-n multi-junction MoSe₂-WSe₂-MoSe₂ heterostructures with intrinsically spatially separated energy landscapes to achieve preferential exciton generation and manipulation without the need for external confinement. In lateral n-p-n field-effect transistor (FET) geometry, we uncover unique and non-trivial electro-optical 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, which enhanced the sensitivity of the proposed device to near-infrared photons. Measurements in different FET device geometries show the multi-functionality 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 on-chip and quantum technologies.

Abstract

Multimodal device operations are essential to advancing the on-chip integration of two-dimensional (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 p-n heterostructures with electrical or strain-induced confinements. In this study, we utilized bilayer 2D lateral n-p-n multi-junction MoSe₂-WSe₂-MoSe₂ heterostructures with intrinsically spatially separated energy landscapes to achieve preferential exciton generation and manipulation without the need for external confinement. In lateral n-p-n field-effect transistor (FET) geometry, we uncover unique and non-trivial electro-optical 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, which enhanced the sensitivity of the proposed device to near-infrared photons. Measurements in different FET device geometries show the multi-functionality 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 on-chip and quantum technologies.