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Vu VT, Phan TL, Vu TTH, Park MH, Do VD, Bui VQ, Kim K, Lee YH, Yu WJ. Synthesis of a Selectively Nb-Doped WS 2-MoS 2 Lateral Heterostructure for a High-Detectivity PN Photodiode. ACS NANO 2022; 16:12073-12082. [PMID: 35913119 DOI: 10.1021/acsnano.2c02242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this study, selective Nb doping (P-type) at the WS2 layer in a WS2-MoS2 lateral heterostructure via a chemical vapor deposition (CVD) method using a solution-phase precursor containing W, Mo, and Nb atoms is proposed. The different chemical activity reactivity (MoO3 > WO3 > Nb2O5) enable the separation of the growth temperature of intrinsic MoS2 to 700 °C (first grown inner layer) and Nb-doped WS2 to 800 °C (second grown outer layer). By controlling the Nb/(W+Nb) molar ratio in the solution precursor, the hole carrier density in the p-type WS2 layer is selectively controlled from approximately 1.87 × 107/cm2 at 1.5 at.% Nb to approximately 1.16 × 1013/cm2 at 8.1 at.% Nb, while the electron carrier density in n-type MoS2 shows negligible change with variation of the Nb molar ratio. As a result, the electrical behavior of the WS2-MoS2 heterostructure transforms from the N-N junction (0 at.% Nb) to the P-N junction (4.5 at.% Nb) and the P-N tunnel junction (8.1 at.% Nb). The band-to-band tunneling at the P-N tunnel junction (8.1 at.% Nb) is eliminated by applying negative gate bias, resulting in a maximum rectification ratio (105) and a minimum channel resistance (108 Ω). With this optimized photodiode (8.1 at.% Nb at Vg = -30 V), an Iphoto/Idark ratio of 6000 and a detectivity of 1.1 × 1014 Jones are achieved, which are approximately 20 and 3 times higher, respectively, than the previously reported highest values for CVD-grown transition-metal dichalcogenide P-N junctions.
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Affiliation(s)
- Van Tu Vu
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Thanh Luan Phan
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Thi Thanh Huong Vu
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Mi Hyang Park
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Van Dam Do
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Viet Quoc Bui
- Department of Chemistry, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Kunnyun Kim
- Korea Electronics Technology Institute, Seongnam, 13509, Republic of Korea
| | - Young Hee Lee
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Woo Jong Yu
- Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
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