Photovoltage Formation Across Si P-N Junction Exposed to Laser Radiation

Photovoltage formation across Si p-n junction exposed to laser radiation is experimentally investigated. Illumination of the junction with 1.06 mu m wavelength laser radiation leads to formation of classical photovoltage U-ph due to intense electron-hole pair generation. When the photon energy is lower than the semiconductor forbidden energy gap, the photovoltage U is found to consist of two components, U = U-f + U-ph. The first U-f is a fast one having polarity of thermoelectromotive force of hot carriers. The second U-ph is classical photovoltage with polarity opposite to U-f. It is found that U-f is linearly dependent on laser intensity. The classical photovoltage is established to decrease with the rise of radiation wavelength due to decrease in two-photon absorption coefficient with wavelength. Predominance of each separate component in the formation of the net photovoltage depends on both laser wavelength and intensity.