Intersubband absorption in boron-doped multiple Ge quantum dots

The intersubband absorption in self-assembled boron-doped multiple Ge quant um dots is observed. The structures used consist of 20 periods of boron-dop ed Ge dot layers and undoped Si barriers. The infrared absorption as a func tion of wavelength is measured by Fourier transform infrared spectroscopy u sing a waveguide geometry. Absorption peaks in the mid-infrared range have been observed, which are attributed to the transitions between the first tw o heavy hole states of the Ge quantum dots. The polarization dependence mea surement is used to study the nature of the transitions. This observation s uggests the possible use of multiple Ge quantum dots for infrared detector application. (C) 1999 American Institute of Physics. [S0003-6951(99)00702-0 ].