Application of optical parametric oscillators to photoacoustic studies in semiconductors

The results of the application of an optical parametric oscillator to photoacoustic studies of semiconductors are reported. The investigation of the photoacoustic signal, waveform and amplitude in Ge, Si, GaAs, GaSb in the 450–1770 nm range allows to make conclusions about the contribution of thermoelastic and deformation mechanisms to pressure pulse formation. At shorter wavelengths, the usual thermoelastic mechanism of acoustic-signal generation is prevailing. At longer wavelengths, for photon energies close to the energy gap, the efficiency of pressure generation in semiconductors with negative deformation potential (Ge, GaAs, GaSb) grows up sharply because of the transition to volume absorption and turning on the deformation mechanism. The experimentally measured values of the photoacoustic pressure are in good agreement with the result of quantitative estimations.