Photovoltaic Infrared Sensor Array in Heteroepitaxial Narrow Gap Lead-Chalcogenides on Silicon

Linear arrays of photovoltaic IR-sensors for thermal imaging applications have been fabricated for the first time in narrow gap semiconductor layers grown heteroepitaxially on Si-substrates. Heteroepitaxy was achieved using intermediate stacked CaF
2
-BaF
2
bilayers to overcome the large lattice- and thermal expansion mismatch between Si and lead-chalcogenides. Sensors fabricated in narrow gap PbTe have ≈5.7 μm cut-off wavelength at 90K and quantum efficiencies around 70%. Resistance-area products are up to 500 Ωcm
²
with mean value of ≈150 Ωcm
²
for 66 element linear arrays, well above the room temperature photon background noise limit. Sensor arrays with shorter cut-off wavelength were fabricated in the same manner in epitaxial Pb
1-x
Eu
x
Se on fluoride covered Si-substrates.