Optical absorption spectroscopy for semiconductors.

摘要

Optical absorption data for a semiconductor sample is dervied by providing a p-type layer (4) of the semiconductor sample between two larger band gap p-type cladding layers (3,5) on an n-type substrate (1). A p-type buffer layer (2) may be present on the substrate (1). Optical radiation is directed towards the p-n junction (6) between the substrate (1) and the buffer layer (2) through a transparent electrode (8) on the outer cladding layer (5). A further electrode (7) contacts the substrate (1) whereby an electric signal can be derived which is related to the voltage generated by the photovoltaic effect at the p-n junction. This signal is indicative of the absorption in the semiconductor sample (4) of the incident radiation in the wavelength range above the absorption edges of both cladding layers and below the wavelength limit at which the p-n junction is sensitive.