Photo-electromotive force

The photoconductivity spectrum after preliminary irradiation of polymer is given by curve 2. The observed redistribution of the peaks is partly reversed on prolonged exposure to air. The bathochromic shift of the shorter wavelength peak depends on the exposure time. Ultraviolet irradiation produces a slight change in the polymer colour. Such irradiation increases, likewise, the photo-electromotive force a 1.5 h irradiation increases it 10 times. The photoconductivity spectrum is situated at longer wavelengths than the photo-electromotive force spectrum. 

A new method for using photo-electromotive force (Photo-EMF) in the detection of gas and for controlling sensitivity is proposed (Vashpanov et al., 2011). Photo-EMF on the heterojunction between the PSi thin layer and the crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A light-transparent contact to the porous Si was formed. Photo-EMF sensitivity corresponding to the ammonia concentration in the range from 10 ppm to 1000 ppm can be controlled by the intensity of the source of illumination. 

Chapter 6. Photo-Electromotive-Force Effect in Semiconductors Sergei Stepanov... 

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