Some Optical Properties of Thin Evaporated Cd₃As₂ Films

Abstract

Abstract The refractive index and absorption coefficient of thin evaporated Cd 3 As 2 films are determinded from spectrophotometric transmission and reflection measurements over the range 0.5 to 12 μm. The refractive index of Cd 3 As 2 is 4.6 at λ = 12 μm; at λ = 1.9 μ a maximum index of n max = 5.3 is observed. In the spectral region 0.5 to 2 μm a sharp decrease is observed in the absorption coefficient, of about two orders of magnitude, from 10 5 cm −1 to 10 3 cm −1 , which may be due to direct transitions. In the range 6 to 12 μm, the absorption coefficient again falls to about 10 2 cm −1 , which probably corresponds to indirect transitions. The results obtained may explain the discrepancies in the values of energy gap quoted by different authors for Cd 3 As 2 .