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Nano Letters· 2026Q1

Visualizing Heteroepitaxy of Angle-Oriented GeSe/WSe2 Heterostructures for Near-Infrared Ultrasensitive Photodetectors

Mengmeng Yang, Shijuan Ran, Shangyu Dai, Jianjun Qiu et al.

Short summary

A visualized, symmetry-guided heteroepitaxy strategy enables precise angle control of GeSe on WSe2, leading to near-infrared photodetectors with a maximum responsivity of 823.8 A/W.

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Key points

  • A visualized heteroepitaxy strategy using in situ imaging and symmetry-guided PVD was developed for GeSe/WSe2.
  • A preferential epitaxial angle of 20° was identified for GeSe on WSe2, corresponding to the energy minimum.
  • Photodetectors achieved a maximum responsivity of 823.8 A/W at 808 nm, a three-order-of-magnitude enhancement.
  • The improved performance is linked to optimized light harvesting and a photogating effect from the type-II band alignment.

AI-generated from the title and abstract; the full text is not read.

Abstract

Abstract Precise heteroepitaxial control in van der Waals (vdW) heterostructures remains a challenge. Here, we demonstrate a visualized and directed heteroepitaxy strategy for GeSe on WSe2 by integrating in situ imaging with symmetry-guided physical vapor deposition. Real-time observation captures the nucleation kinetics and orientation evolution, accelerating process optimization. Combined density functional theory calculations and transmission electron microscope characterizations identify a preferential epitaxial angle of 20° (occurrence: 59.37%) for most GeSe nanosheets, corresponding to the global energy minimum governed by lattice symmetry. Coverage-tunable photodetectors are constructed by modulating GeSe nanosheets’ number, delivering a three-orders-of-magnitude enhancement in responsivity at 808 nm (823.8 A/W at maximum coverage). This is attributed to optimized light harvesting in GeSe and a photogating effect via back-to-back type-II band alignment. High-contrast single-pixel imaging is also demonstrated. This work establishes a paradigm for visualized synthesis and performance optimization of monochalcogenide-based vdW heterostructures.

The authors' abstract, as published at the source. Nano Letters, 2026 · DOI ↗

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Field: Materials Chemistry

Materials ChemistryMaterials Science