InAs/(GaIn)Sb superlattices for infrared detection

We report on the growth and characterization of InAs/(GaIn)Sb superlattices (SLs) as well as on the fabrication and testing of SL infrared (IR) photodiodes. InAs/Ga(0.8)In(0.2)Sb SLs with individual layer thicknesses of 12 and 10 monolayers, respectively, were grown by molecular-beam epitaxy either directly on GaSb substrates or on GaAs substrates using a strain-relaxed GaSb buffer layer. To achieve strain compensation, SL growth was performed with alternating InSb-like and GaAs-like interfaces. IR n-on-p photodiodes employing a strain-optimized InAs/(GaIn)Sb SL as the active region were fabricated using standard III-V technology. SL photodiodes with cut-off wavelengths in the 7.5 to 8.5 mu m wavelength range showed at 77 K responsivities of 2 A/W and R0A products exceeding 10(exp3) ohm cm2.