Hole intersubband absorption in δ-doped multiple Si layers

The hole intersubband infrared absorption in δ-doped Si multiple quantum wells is observed for the first time. The structures used consist of ten periods of boron-doped Si quantum wells and undoped Si barriers. Near 100% infrared absorption is measured by a Fourier transform infrared spectrometer using waveguide structures. The observed absorption peaks ranging between 3 and 7 μm, which are mainly due to the transition between the first two heavy hole subbands. This absorption peak can be tuned by varying the doping concentration in the δ-doped layer. The polarization-dependent spectra show good agreement with the intersubband selection rule. The estimated peak energy positions using a self-consistency calculation with exchange effects as a perturbation agree reasonably well with the experimental observation. This observation suggests the use of multiple quantum well for IR detector application using Si technology