[article-cris] Sähkötekniikan korkeakoulu / ELEC

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Browsing [article-cris] Sähkötekniikan korkeakoulu / ELEC by Subject "2-DIMENSIONAL MATERIALS"

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  • Direct Epitaxial Growth of InP Nanowires on MoS2 with Strong Nonlinear Optical Response
    (2022-10-25) Shafi, Abde Mayeen; Das, Susobhan; Khayrudinov, Vladislav; Uddin, Md Gius; Ding, Er-Xiong; Ahmed, Faisal; Sun, Zhipei; Lipsanen, Harri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Mixed-dimensional van der Waals heterostructures are promising for research and technological advances in photonics and optoelectronics. Here we report vapor-liquid-solid (VLS) method -based van der Waals epitaxy of one-dimensional InP nanowires (NWs) directly on two-dimensional MoS2. With optimized growth parameters (V/III ratio, flow rates of precursors, and growth temperature), we successfully grow high-quality InP NWs on MoS2. The density and vertical yield of NWs on MoS2 are significantly high. Due to the unique properties of both materials, we observe strong linear and nonlinear optical responses from the NW/MoS2 heterostructures. Intriguingly, in addition to strong second and third harmonic responses, the mixed-dimensional heterostructures show odd-order high harmonic generation up to seventh order. Our findings can open new possibilities for advancing attosecond physics on a new platform of mixed-dimensional heterostructures.
  • Tunable Quantum Tunneling through a Graphene/Bi2Se3 Heterointerface for the Hybrid Photodetection Mechanism
    (2021-12-15) Yoon, Hoon Hahn; Ahmed, Faisal; Dai, Yunyun; Fernandez Pizarro, Henry; Cui, Xiaoqi; Bai, Xueyin; Li, Diao; Du, Mingde; Lipsanen, Harri; Sun, Zhipei
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Graphene-based van der Waals heterostructures are promising building blocks for broadband photodetection because of the gapless nature of graphene. However, their performance is mostly limited by the inevitable trade-off between low dark current and photocurrent generation. Here, we demonstrate a hybrid photodetection mode based on the photogating effect coupled with the photovoltaic effect via tunable quantum tunneling through the unique graphene/Bi2Se3 heterointerface. The tunneling junction formed between the semimetallic graphene and the topologically insulating Bi2Se3 exhibits asymmetric rectifying and hysteretic current-voltage characteristics, which significantly suppresses the dark current and enhances the photocurrent. The photocurrent-to-dark current ratio increases by about a factor of 10 with the electrical tuning of tunneling resistance for efficient light detection covering the major photonic spectral band from the visible to the mid-infrared ranges. Our findings provide a novel concept of using tunable quantum tunneling for highly sensitive broadband photodetection in mixed-dimensional van der Waals heterostructures.