High-responsivity thermoelectric infrared detectors with stand-alone sub-micrometer polysilicon wires

Abstract

A novel high-responsivity uncooled thermoelectric (TE) infrared (IR) detector is designed, fabricated and characterized. This detector features a single stand-alone polysilicon-based thermocouple (without a supporting membrane) covered by an umbrella-like optical cavity IR absorber. It is proved that the highest responsivity in the developed detectors can be achieved with only one thermocouple. Using a single thermocouple also results in a low resistance detector, which consequently limits the Johnson noise (e.g. less than 30 nv/√Hz in this work). Since the sub-micrometer polysilicon TE wires are the only heat path from the hot junction to the substrate, a superior thermal isolation is achieved. A responsivity of 1800 V W−1 and a detectivity of 2* 108 (cm Hz1/2 W−1) are measured from a 20 × 20 µm detector comparable to the performance of detectors used in commercial focal planar arrays []. This performance in a compact and manufacturable design elevates the position of thermoelectric IR sensors as a candidate for low-power, high performance and inexpensive focal planar arrays.

Thermal conductivity characterization of in-situ fabricated polysilicon nanowires for uncooled thermoelectric infrared detectors

“…This reduction in thermal conductivity of nanowires is mainly a result of phonon boundary scattering [3]. As shown previously [1], ZT/K is a more suitable figure of merit for thermoelectric materials utilized in sensing applications since no power is extracted out of the device and the focus is mainly on electric field/or voltage generation. ZT/K or shows that reducing the thermal conductivity is more important for sensors compared to power generation applications.…”

“…ZT/K or shows that reducing the thermal conductivity is more important for sensors compared to power generation applications. We have previously shown high performance uncooled thermoelectric infrared detectors utilizing doped polysilicon as the thermoelectric materials [1]. Polysilicon films are relatively easy to deposit and pattern as opposed to silicon.…”

Performance enhance of CMOS-MEMS thermoelectric infrared sensor by using sensing material and structure design

“…where ε is the emissivity, σ is the Stefan-Boltzmann constant (5.6697 × 10 −8 W m −2 K −4 ), A is the area of absorber, T 1 is the temperature of emitter (object), and T 0 is the temperature of absorber (sensor) [29]. As indicated in figure 1(a), according to the Seebeck effect [28], the output voltage ΔV yielded from thermopile can be expressed as [23],…”

“…Moreover, various CMOS-MEMS thermoelectric IR sensors have also been demonstrated [22][23][24][25][26][27]. By using the available CMOS thin film materials and layers stacking, the performance of thermoelectric IR sensor has been improved through the designs of thermocouple [22,23] and structures [7,12,13,27,28]. To enhance the performance of the CMOS-MEMS thermoelectric IR sensor, this study proposed the design of an umbrella-like structure as an IR absorber.…”

Metasurfaces for Enhancing Light Absorption in Thermoelectric Photodetectors

“…The detection of light in the broad spectral regime ranging from the visible to the short-wave infrared has gained renewed attention in the past decade. Among many types of devices, thermoelectric devices − have been utilized by exploiting their capability to transduce between thermal and electrical signals. Electromagnetic radiation absorbed by these devices is converted to heat, thereby raising the temperature of the device.…”