image: Schematic and characterization of a suspended nanometer-thick SrTiO3 photothermoelectric detector. The architecture reduces active thermal mass, preserves lateral temperature gradients and enables dual-gate control of the Seebeck coefficient.
Credit: ©Science China Press
Mid-infrared cameras can see thermal radiation rather than reflected visible light, making them valuable for night vision, environmental monitoring, autonomous navigation and other low-visibility sensing tasks. A key goal for next-generation infrared vision is to move part of the image-processing workload into the sensor itself, so that useful thermal information can be filtered, enhanced or weighted before large amounts of data are sent to external processors.
A research team now reports a programmable photothermoelectric detector based on a suspended nanometer-thick SrTiO3 membrane. The study addresses a central trade-off in infrared sensing. Thermal detectors can operate at room temperature and cover broad spectral ranges, but their speed is often limited by heat transport. Programmable mid-infrared detectors, meanwhile, commonly rely on narrow-bandgap materials whose stable and reconfigurable operation can be difficult to maintain.
The new device uses a suspended SrTiO3 thin film as the thermoelectric channel. Scaling the channel down to the nanometer range reduces active thermal mass, while the suspended structure helps preserve lateral temperature gradients that drive the photothermoelectric response. As a result, the detector shows a broadband zero-bias photovoltage response from visible wavelengths to about 10 micrometers and a response time of about 10 microseconds, more than 10,000 times faster than the bulk SrTiO3 photothermoelectric devices discussed in the study.
The team further introduced two local bottom gates beneath the suspended channel. By applying opposite voltages to the two gates, the researchers can create a controllable thermoelectric contrast across the channel, allowing both the strength and polarity of the infrared response to be programmed. This control originates from electrostatic modulation of the local Seebeck coefficient. Under infrared illumination, the device reaches a responsivity of about 50 volts per watt and provides 40 experimentally measured stable response states.
To test whether the concept can be extended beyond a single detector, the researchers fabricated a 3-by-3 array of suspended SrTiO3 devices. The array shows reproducible gate-programmable polarity switching and can be configured as convolutional kernels for infrared image preprocessing, including inverse, difference-of-Gaussian and Laplacian operations. The study also demonstrates attention-guided thermal target enhancement using experimentally measured responsivity states. This part of the work is based on dataset-driven, off-chip reconstruction rather than a complete real-time recognition system integrated on chip.
The results establish suspended nanometer-thick perovskite-oxide thermoelectrics as a candidate platform for reconfigurable infrared vision, in-sensor preprocessing and intelligent infrared electronics.