High-Sensitivity Temperature Measurement With Miniaturized InSb Mid-IR Sensor

Abstract

This paper reports the development and evaluation of an InSb photovoltaic infrared sensor (InSb PVS) operating at room temperature. The InSb PVS consists of 700 InSb p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> - p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> - n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> photodiodes connected in series, on a semi-insulating GaAs (100) substrate. An Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.17</sub> rIn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.83</sub> Sb barrier layer between p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> and p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> layers was used to reduce diffusion of photo-excited electrons. Cutoff wavelength was 6.8 mum and output signal was almost linear with irradiance up to 0.6 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Sensitivity of 67 muV/K and noise equivalent temperature difference of 2.2 mK/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> was obtained at room temperature, which shows the sensor to be a suitable for noncontact thermometry.