Abstract

Defects in atomically thin materials can drive new functionalities and expand applications to multifunctional systems that are monolithically integrated. An ability to control formation of defects during the synthesis process is an important capability to create practical deployment opportunities. Molybdenum disulfide (MoS₂), a two-dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS2, while maintaining the structural integrity of the crystals remains a notable challenge. Here, we present a one-step, in-situ defect engineering approach for monolayer MoS₂ using a pressure dependent chemical vapour deposition (CVD) process. Monolayer MoS₂ grown in low-pressure CVD conditions (LP-MoS₂) produces sulfur vacancy (Vs) induced defect rich crystals primarily attributed to the kinetics of the growth conditions. Conversely, atmospheric pressure CVD grown MoS₂ (AP-MoS₂) passivates these Vs defects with oxygen. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP-MoS₂ shows a drastically enhanced photoluminescence, which is significantly quenched in LP-MoS₂ attributed to in-gap electron donor states induced by the Vs defects. However, the n-doping induced by the Vs defects in LP-MoS₂ generates enhanced photoresponsivity and detectivity in our fabricated photodetectors compared to the AP-MoS₂ based devices. Defect-rich LP-MoS₂ outperforms AP-MoS₂ as channel layers of field-effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single-step CVD approach for in-situ defect engineering in monolayer MoS₂ and presents a pathway to control defects in other monolayer material systems.

Abstract

Defects in atomically thin materials can drive new functionalities and expand applications to multifunctional systems that are monolithically integrated. An ability to control formation of defects during the synthesis process is an important capability to create practical deployment opportunities. Molybdenum disulfide (MoS₂), a two-dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS2, while maintaining the structural integrity of the crystals remains a notable challenge. Here, we present a one-step, in-situ defect engineering approach for monolayer MoS₂ using a pressure dependent chemical vapour deposition (CVD) process. Monolayer MoS₂ grown in low-pressure CVD conditions (LP-MoS₂) produces sulfur vacancy (Vs) induced defect rich crystals primarily attributed to the kinetics of the growth conditions. Conversely, atmospheric pressure CVD grown MoS₂ (AP-MoS₂) passivates these Vs defects with oxygen. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP-MoS₂ shows a drastically enhanced photoluminescence, which is significantly quenched in LP-MoS₂ attributed to in-gap electron donor states induced by the Vs defects. However, the n-doping induced by the Vs defects in LP-MoS₂ generates enhanced photoresponsivity and detectivity in our fabricated photodetectors compared to the AP-MoS₂ based devices. Defect-rich LP-MoS₂ outperforms AP-MoS₂ as channel layers of field-effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single-step CVD approach for in-situ defect engineering in monolayer MoS₂ and presents a pathway to control defects in other monolayer material systems.

Abstract

Defects in atomically thin materials can drive new functionalities and expand applications to multifunctional systems that are monolithically integrated. An ability to control formation of defects during the synthesis process is an important capability to create practical deployment opportunities. Molybdenum disulfide (MoS₂), a two-dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS2, while maintaining the structural integrity of the crystals remains a notable challenge. Here, we present a one-step, in-situ defect engineering approach for monolayer MoS₂ using a pressure dependent chemical vapour deposition (CVD) process. Monolayer MoS₂ grown in low-pressure CVD conditions (LP-MoS₂) produces sulfur vacancy (Vs) induced defect rich crystals primarily attributed to the kinetics of the growth conditions. Conversely, atmospheric pressure CVD grown MoS₂ (AP-MoS₂) passivates these Vs defects with oxygen. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP-MoS₂ shows a drastically enhanced photoluminescence, which is significantly quenched in LP-MoS₂ attributed to in-gap electron donor states induced by the Vs defects. However, the n-doping induced by the Vs defects in LP-MoS₂ generates enhanced photoresponsivity and detectivity in our fabricated photodetectors compared to the AP-MoS₂ based devices. Defect-rich LP-MoS₂ outperforms AP-MoS₂ as channel layers of field-effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single-step CVD approach for in-situ defect engineering in monolayer MoS₂ and presents a pathway to control defects in other monolayer material systems.

Abstract

Defects in atomically thin materials can drive new functionalities and expand applications to multifunctional systems that are monolithically integrated. An ability to control formation of defects during the synthesis process is an important capability to create practical deployment opportunities. Molybdenum disulfide (MoS₂), a two-dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS2, while maintaining the structural integrity of the crystals remains a notable challenge. Here, we present a one-step, in-situ defect engineering approach for monolayer MoS₂ using a pressure dependent chemical vapour deposition (CVD) process. Monolayer MoS₂ grown in low-pressure CVD conditions (LP-MoS₂) produces sulfur vacancy (Vs) induced defect rich crystals primarily attributed to the kinetics of the growth conditions. Conversely, atmospheric pressure CVD grown MoS₂ (AP-MoS₂) passivates these Vs defects with oxygen. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP-MoS₂ shows a drastically enhanced photoluminescence, which is significantly quenched in LP-MoS₂ attributed to in-gap electron donor states induced by the Vs defects. However, the n-doping induced by the Vs defects in LP-MoS₂ generates enhanced photoresponsivity and detectivity in our fabricated photodetectors compared to the AP-MoS₂ based devices. Defect-rich LP-MoS₂ outperforms AP-MoS₂ as channel layers of field-effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single-step CVD approach for in-situ defect engineering in monolayer MoS₂ and presents a pathway to control defects in other monolayer material systems.