Free-carrier absorption in Be- and C-doped GaAs epilayers and far infrared detector applications

Far infrared (FIR) absorption, reflection, and transmission in heavily doped p-GaAs multilayer structures have been measured for wavelengths 20-200 mum and compared with the calculated results. Both Be (in the range 3x10(18)-2.6x10(19) cm(-3)) and C (1.8x10(18)-4.7x10(19) cm(-3))-doped structures were studied. It is found that the observed absorption, reflection, and transmission are explained correctly by the model with a dominant role of free-carrier absorption in highly doped regions. High reflection from heavily doped thick layers is attractive for the resonant cavity enhanced FIR detectors. (C) 2001 American Institute of Physics.