Abstract

A detector with two distinct superlattices separated by a blocking barrier was investigated for multi-wavelength infrared detection. Figure 1 shows the band structure of our detector. It contains sequentially a 300 nm bottom contact layer, a 14-period bottom superlattice, a blocking barrier, another 14-period top superlattice, and a 400 nm top contact layer. Each period of the bottom and top superlattices is respectively composed of 6 nm GaAs well and 4 nm Al_{0 27}Ga_{0 73)}As barrier, and 4.5 nm GaAs well and 6 nm Al_0.31Ga_0.69As barrier. The blocking barrier consists of a 60 nm Al_0.27Ga_0.73As layer, a 50 nm graded Al_xGa_1−xAs layer with x increasing from 0.27 to 0.31, and a 60 nm Al_0.31Ga_0.69As layer. Both the contact layers and the superlattice wells are doped with 1 × 10^l8 cm⁻³ of Si. The blocking barrier and the superlattice barriers are left undoped.

© 2002 Optical Society of America