Interfacial Synergy in a Band-Aligned Low-Dimensional Heterojunction Toward Broadband Photodetection.

Area of Science:

• Materials Science
• Photonics
• Semiconductor Physics

Background:

• Monolithic integration of sensing, imaging, and communication across visible to terahertz bands is challenging due to incompatible material requirements.
• Conventional semiconductors have bandgap limitations or require cryogenic cooling, while low-dimensional heterojunctions struggle with multiband response and carrier recombination.

Purpose of the Study:

• To demonstrate a novel low-dimensional heterojunction for ultrabroadband photodetection.
• To achieve efficient and low-noise detection across visible to terahertz regimes on a single chip.
• To explore applications in reconfigurable logic and dual-channel communication.

Main Methods:

• Fabrication of a band-aligned heterojunction using Ta2NiSe5 and Sb2Te3.
• Characterization of photoresponse across visible to terahertz spectra.
• Antenna-enhanced coupling for terahertz detection.
• Analysis of interfacial synergy and built-in potential effects.

Main Results:

• Achieved ultrabroadband photodetection from visible to terahertz with stable responsivities up to 0.19 A·W⁻¹ in the visible-near-infrared.
• Demonstrated microsecond transients, 10 kHz bandwidth, and noise-equivalent power of 26 pW·Hz⁻¹/² in the terahertz range.
• Utilized a Type-II band alignment (115 meV built-in potential) for efficient carrier separation and photothermal effects.

Conclusions:

• The Ta2NiSe5/Sb2Te3 heterojunction enables synergistic ultrabroadband photodetection.
• The device shows potential for multifunctional photonic systems, including reconfigurable logic and dual-channel communication.
• This work overcomes limitations of conventional materials for integrated optoelectronic systems.