Photoconductivity in YIG Doped with Si, Ca and Sr

Abstract

Photoconductivity is measured on YIG as functions of light intensity, electric field, temperature and doping concentrations of Si⁴⁺ and Sr²⁺ The experimental results are summarized as follows:
(1) Shape of relaxation curves depends on the intensity of the exciting light and the decay time increases with light intensity.
(2) Dark current and photocurrent have a similar thermal behavior; both of them increase exponentially with temperature. This may be predominantly due to the thermal variation of the mobility of electrons, μ.
(3) Photocurrent is proportional to the intensity of light below approximately 250°K and at higher temperatures saturation begins.
(4) Spectral response of the photoconductivity shows a rise at shorter wavelengths of exciting visible light, corresponding to an absorption edge roughly in 5 mol% Si-doped YIG. Also, the subpeak of photocurrent at the photon energy of 1.4 eV roughly corresponds to the optical absorption peak.
(5) Photosensitivity Ps (the ratio of photocurrent to dark current) decreases with an increase of Si⁴⁺ dopant and increases with concentration of Ca²⁺ or Sr²⁺.