Depolarization current behavior of photo-magneto-electrets of polycrystalline sulphur

In the present study depolarization (dark and photo) current behavior of Photo-Magneto-Electrets (PMEs for short) of polycrystalline sulphur have been reported. Sulphur samples are subjected to a combination of magnetic field and optical radiation. Samples prepared in presence of different magnetic fields ranging from 0.00, 2.25, 7.05, 12.1, and 16.1 K. Gauss, with constant intensity of light radiations, 1000 and 2000 lux. The photo depolarization is done with mercury light, whereas dark depolarization carried out by storing the samples in dark. Photo-depolarization current decay is directly proportional to the intensity of illumination, over the range of 0, 500, 1000, 1500 and 2000 lux. Photo-depolarization obeys an exponential law and is more rapid for the samples prepared at stronger magnetic fields. This suggests that the formation of PME state may be due to electrons trapped in structural defects. The variation of decay current with time is investigated in detail, and is explained quantitatively in terms of charge remaining in sample. Further, the PME samples of sulphur were, depolarized by illuminating them with radiations of different frequencies (i.e. 365, 405, 436, 546 μm). The effects of frequency of depolarizing radiations, frequency of mercury emission spectra were used. According to this the depolarization observed with shorter wavelength radiations obeys an exponential law. In this way the decay rate is more than that observed for the higher frequency illuminations. Variations of depolarization current of PMEs, shows a sharp maximum and then current decays, becoming constant in about ten minutes. Total area below the curves gives the amount of total charge stored. And the depolarization current verses time curves, give an idea about the volume polarization in the dielectric. Measurement of depolarization current gives an important insight about the physics of dielectric materials, like mapping of charge inside the electret.