Effect of chemical etching on photoinduced modulation of subterahertz radiation by crystalline germanium

Abstract. The influence of the etching duration on the surface of Ge samples with different thicknesses (0.5, 1.6, and 2.3 mm) on their photomodulation of terahertz radiation with a frequency of f = 130 GHz was investigated. It was shown that pulsed lamp illumination of Ge samples with a thickness of 0.5 mm, chemically etched in a solution of 95 cm³ of 1% KOH and 75 cm³ of 60% H₂O₂ for different durations (3 and 42 min), leads to changes in the transmission of electromagnetic radiation: a decrease after 3 min and an increase after 42 min. In contrast, the etching of Ge samples with thicknesses of 1.6 mm and 2.3 mm results in a decrease in their electromagnetic radiation transmission upon illumination.