EFFECT OF A LOW CHROMIUM IMPURITY ON PROPERTIES OF PHOTOINDUCED CHARGE CARRIERS IN BI12TIO20 AND BI12SIO20 SINGLE CRYSTALS

摘要

The influence of low (similar to 10(-4) wt.%) chromium concentrations on the photorefractive properties of sillenite crystals have been studied by holographic techniques. The presence of chromium decreases the diffusion length of photoexcited carriers in both Bi12SiO20 and Bi12TiO20 crystals, whereas the Debye screening length decreases only in BSO samples. This means that the chromium present in BTO crystals does not increase the number of the free traps. Small concentrations of chromium in BSO crystal displace the maximum of the gain factor to higher spatial frequencies that could be useful for some applications. [References: 8]