Self-powered p-GeTe/n-MoS2 heterojunction on flexible substrate for high-performance broadband photodetectors
This study reports a self-powered broadband photodetector based on a p-GeTe/n-MoS2 heterojunction fabricated on Si/SiO2 and flexible polyimide substrates. The heterojunction leverages efficient light absorption and charge separation via a built-in electric field, enabling operation without external bias. At 405 nm, the device achieves a peak responsivity of 3877 A/W and a detectivity of 8.1 × 10^12 Jones, with rise and fall times of 0.45 s and 0.28 s, respectively. Under 808 nm illumination, responsivity reaches 1.28 A/W and detectivity 1.2 × 10^9 Jones. The flexible device exhibits stable photoresponse over 500 bending cycles, maintaining consistent dark current and photocurrent. Fabrication combines RF magnetron sputtering for GeTe and dry transfer for MoS2, yielding a scalable route to flexible optoelectronics. The p-GeTe/n-MoS2 heterojunction addresses the limitations of conventional rigid photodetectors, offering a viable path for wearable sensing and broadband imaging. The results demonstrate that the heterojunction maintains high performance across visible to near-infrared wavelengths, with mechanical robustness suitable for integration into diverse optoelectronic systems.