Two-dimensional monolithic lead chalcogenide infrared sensor array on silicon read-out chip

A complete 2-d narrow gap infrared focal plane array on a Si-substrate where the Si-substrate contains the active addressing electronics was realized. Narrow gap IV–VI (lead chalcogenides like PbTe) layers grown epitaxially on Si(1 1 1)–substrates by molecular beam epitaxy serve as infrared sensitive detectors. The array consists of 96×128 pixels with 75 μm pitch, and cut-off wavelength is 5.5 μm. It allows row-by-row electronic scanning and parallel read-out of the line addressed. The chips are fabricated by CMOS-technology with standard Al-metallization. Each pixel contains a bare Si-area onto which epitaxial growth occurs, and an access transistor. Yield in completely fabricated arrays was above 98%, with quantum efficiencies around 60%, and mean differential resistances at zero bias up to 4 MΩ at 95 K.