In this paper we describe the design of a high resolution nearhyphen;infrared photoacoustic spectrometer of the gashyphen;microphone type intended to be used for measuring impurity absorption spectra of semiconductors. Particular attention has been paid to the design of the photoacoustic cell to find the most suitable one, and as a result, several cells differing in geometry and materials have been investigated. We present results for the PA amplitude dependence on the modulating frequency for carbon black powder and some widely used semiconductors. The sensitivity of the spectrometer and its effectiveness in resolving active defect states existing in the subgap absorption spectra of semiconductors are demonstrated in both optically opaque and transparent thick and thin samples.
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