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

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
⁺
- p
^-
- n
⁺
photodiodes connected in series, on a semi-insulating GaAs (100) substrate. An Al
_0.17
rIn
_0.83
Sb barrier layer between p
⁺
and p
^-
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
²
. Sensitivity of 67 muV/K and noise equivalent temperature difference of 2.2 mK/Hz
^1/2
was obtained at room temperature, which shows the sensor to be a suitable for noncontact thermometry.