What question did this study set out to answer?

This research aims to optimize the performance of broadband photodetectors using asymmetric electrode designs.

January 25, 2026

Asymmetric Electrode Engineering in p‐Si/n‐SnSSe Heterojunction Photodetectors for Enhanced Broadband Responsivity and Self‐Powered Operation

Key Points

This research aims to optimize the performance of broadband photodetectors using asymmetric electrode designs.
Developed p-Si/n-Sn(SxSe1-x)2 vertical heterojunction photodetectors.
Investigated four device configurations: symmetric and asymmetric electrodes.
Measured responsivity, external quantum efficiency, and detectivity at specific wavelengths.
Examined the role of electrode asymmetry on carrier dynamics.
Achieved a responsivity of 1.01 A/W and external quantum efficiency of 197.29%.
Demonstrated a specific detectivity of 3.75 × 10^11 Jones at 635 nm.
D3 device operated self-powered, generating 16.6 nA at 0 V under white light.
Devices showed a broadband response from 505–940 nm with high sensitivity.

Abstract

Abstract Advanced imaging, sensing, andtelecommunications demand high‐performance, low‐power broadband photodetectorswith improved responsivity and spectral range. This work fills a key gap bydemonstrating p‐Si/n‐Sn(S x Se 1‐x ) 2 verticalheterojunction (HJ) photodetectors with asymmetric Ag (Φ = 4.28 eV) /graphene(Φ = 4.7 eV) electrodes to optimize carrier dynamics and band alignment. Fourdevice configurations; symmetric (D1: Ag/HJ/Ag, D2: Gr/HJ/Gr) and asymmetric(D3: Gr/HJ/Ag, D4: Ag/HJ/Gr) were systematically investigated to elucidate therole of electrode asymmetry in enhancing photoresponse. D4 achievesstate‐of‐the‐art responsivity of 1.01 A/W, external quantum efficiency (EQE) of 197.29%, and specific detectivity of 3.75 × 10 11 Jones at 635 nm(130 µW/cm 2 , +3 V), driven by efficient hole injection at Ag/p‐Si (Φ Bp ≈ 0.87 eV) and electron extraction at Gr/n‐SnSSe (Φ Bn ≈ 0.38 eV), augmented by photoconductive gain from trap‐assisted carrier multiplication.The D3 device operates self‐powered, producing 16.6 nA at 0 V under white lightdue to a strong built‐in field from the Gr/Ag work‐function contrast. Thedevices show broadband response (505–940 nm) with high sensitivity performanceeven at low light intensities (<150 µW/cm 2 ). This work presentsa scalable, material‐efficient route to high‐efficiency self‐poweredphotodetectors for energy‐efficient broadband sensing.

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