Thermoelectric bolometers based on ultra-thin heavily doped single-crystal silicon membranes

TL;DR

This paper introduces ultra-thin, heavily doped silicon membrane thermocouple bolometers that enable fast, sensitive detection of low thermal power and infrared radiation at room temperature, with high sensitivity and low noise.

Contribution

The work demonstrates a novel silicon membrane bolometer design with high sensitivity and fast response, operating near the thermodynamic noise limit.

Findings

Noise equivalent power of 13 pW/rtHz

Thermal time constant of 2.5 ms

High Seebeck coefficient of 0.39 mV/K

Abstract

We present ultra-thin silicon membrane thermocouple bolometers suitable for fast and sensitive detection of low levels of thermal power and infrared radiation at room temperature. The devices are based on 40 nm-thick strain tuned single crystalline silicon membranes shaped into heater/absorber area and narrow n- and p-doped beams, which operate as the thermocouple. The electro-thermal characterization of the devices reveal noise equivalent power of 13 pW/rtHz and thermal time constant of 2.5 ms. The high sensitivity of the devices is due to the high Seebeck coefficient of 0.39 mV/K and reduction of thermal conductivity of the Si beams from the bulk value. The bolometers operate in the Johnson-Nyquist noise limit of the thermocouple, and the performance improvement towards the operation close to the temperature fluctuation limit is discussed.