FAR-INFRARED SPECTRA OF REFLECTIVITY, TRANSMISSION AND HOT-HOLE EMISSION IN P-DOPED GAAS AL0.5GA0.5AS MULTIPLE-QUANTUM WELLS/

Far-infrared reflectivity and transmission spectra have been measured for p-doped GaAs/Al0.5Ga0.5As multiple quantum wells (MQWs) using pola rized oblique-incidence Fourier transform spectroscopy (FTS). Theoreti cal calculations have been performed within a bulk slab effective-medi um scheme, modified to include an anisotropic plasma response in the w ells, and successfully compared with the experimental data. The optics of the observed features are discussed, with particular reference to interference modes. Far-infrared intersubband absorption at 80 cm(-1) was observed by Brewster's angle (theta = 73 degrees) transmission mea surements. Furthermore, we present the first observation of far-infrar ed emission by two-dimensional hot holes in MQWs due to heating of hol es by a longitudinal electric field applied along the layers. The obse rved emission energies are attributed to direct transition of hot hole s between subbands of the valence band due to size quantization.