Absorption coefficients of In0.8Ga0.2As at room temperature and 77 K

•Energy dependent absorption coefficients of In0.8Ga0.2As at RT and 77 K obtained.•Absorption of In0.53Ga0.47As also measured and compared to references.•Temperature and composition dependent absorption features of InGaAs discussed.

The absorption coefficients of high Indium content In0.8Ga0.2As at room temperature and 77 K have been obtained from transmission measurements by using the Fourier transformed infrared spectrometer. A high precision can be ensured for the deduced absorption coefficient value in the most interested wavelength range, through the appropriate sample design and measurement scheme selection. The absorption features of InGaAs at different temperatures and compositions are discussed. For ternary InxGa1−xAs, the absorption coefficient at a specific composition could be achieved by translating the data from a known composition, whereas it should be careful to translate the absorption coefficients between different temperatures even for a fixed composition.