Dual-mode infrared detection via photovoltaic and barrier pyroelectric effects in PbTe <i>p</i> – <i>n</i> junctions

Abstract

In the work, two effects appeared in PbTe p–n junctions under mid-wavelength infrared (2 − 5 μm) and long-wavelength infrared irradiation (≈10.6 μm). The first effect was created by the optical absorption of lR-photons in PbTe and caused by its photovoltage effect. The second novel effect is related to the heating process and the formation of a temperature difference at the p–n junction. The main feature of the PbTe semiconductor is a strong temperature dependence of the static dielectric constant ε. In this case, for the PbTe p–n junction, a barrier pyroelectric effect is created. The PbTe p–n junctions were fabricated employing indium donor diffusion in single crystals of PbTe grown using the Czochralski technique. Current–voltage and capacitance–voltage characteristics have been measured over a wide temperature range. The dark saturation current density was ∼10−7 A/cm2 at T = 100 K. The blackbody radiation was used for the investigation of the photovoltaic effect. Continuous irradiation of CO2 was used to study the thermal effect and caused by its barrier pyroelectric effect. These two effects were investigated in the 40–190 K temperature range. As a result, we present the design, fabrication, and characterization of a single PbTe p–n junction that successfully integrates both photovoltaic and pyroelectric detection mechanisms, with the aim of creating a novel high-performance infrared detector.