<報文>天然黄鉄鉱の半導体的特性(第4報) : 光学的遷移の観測

概要

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Measurements of the absorption spectrum of natural pyrite crystal (having the thickness from 12 to 85 μm) have been carried out over the wavelength range from 0.7 to 2.5 μm at room temperature. The absorption coefficient seems to be grouped by the ore deposit. The steep rise in the plots of the absorption coefficient a vs photon energy hυ has been observed around 0.9 eV at room temperature. This steep rise seems to indicate the region near the absorption edge. The plots of α^2 vs hυ in this region suggest the onset of the direct transition. Reflection spectra for the same crystals used for the absorption measurement have been observed at room temperature over the energy range from 0.5 to 6 eV by the double beam method. The reflectivity differs below about 1 eV for each crystal. The imaginary part of the refractive index, which was computed from the reflection spectrum using the Kramers-Kronig relations, has small steps near 0.7 and 1 eV. The computed index, however, is changed according to the difference of the extrapolation constants which are determined on the higher-energy side of the reflection spectrum. Results of photoconductivity experiments are also described briefly. The peak observed near 0.9 eV for each crystal is attributed to the interband-direct transition. The peak shifts to the higher-energy side with the temperature change from 77°K to 4.2°K.
東北大学の論文
1975-03-25