Optical properties of aluminum dodecaboride (α-AlB12) in the region of the transparency window

Abstract

The absorption coefficient of α-AlB12 was measured on single crystal samples at T=300 K within a broad spectral region (0.6–25 µm). In the region of the transparency window (3–6 µm), the absorption coefficient was measured in the temperature range from 165 to 650 K. An analysis of the experimental data shows that the energy spectrum of local states in the α-AlB12 bandgap has certain features. It was established that a broad band of local states lies near the conduction band and that a trap level is located at 0.11±0.02 eV from the top of the valence band.