THERMAL-RADIATION ABSORPTION IN DOPED SEMICONDUCTORS DUE TO DIRECT INTERSUBBAND TRANSITIONS

This work proposes an engineering model for thermal radiation absorpti on due to direct intersubband transitions in eloped semiconductors, wh ich are excitations of bound electrons in the infrared spectral region . An existing quantum-mechanical approach is to model these transition s as a continuum of damped harmonic oscillators. This study modifies t his approach to yield a more effective method for determining the opti cal constants of doped semiconductors. The room-temperature absorptanc e spectra of p-type Gags samples with dopant concentrations from 8 X 1 0(17) to 1 X 10(20) cm(-3) are measured using a Fourier transform-infr ared spectrometer in the spectral region from 1.5 to 25 mu m. The fitt ing of these spectra using the proposed model combined with the Drude and Lorentz models provides tire optical constants and the dependence of the adjustable parameters on dopant concentration. The measured and fitted spectra agree closely. Potential applications of the model are semiconductor process control and infrared detector design.