Infrared photovoltaic detectors from ion-implanted CdxHg1−xTe

We have fabricated n-p photovoltaic detectors in CdxHg1−xTe using aluminum implantation to create the n-type region. Implanted diodes made in this material with a composition x = 0.18, which corresponds to a band gap of 0.1 eV, had a zero-bias resistance of 1 kΩ at 77°K for a 200 × 250-μm sensitive area. The spectral response was almost flat in the range 4–12 μm with a quantum efficiency as high as 57% at 10.6 μm. The measured detectivity for a 30° field of view is 7.3 × 1010 cm Hz1/2 W−1 at 10.6 μm. This is one of the highest detectivities ever reported at this wavelength. Finally, the frequency response of these diodes used in a heterodyne detection system operating with a CO2 laser was 1 GHz.