Comparison between holographic and transient-photocurrent measurements of electron mobility in photorefractive Bi12SiO20

We have developed a time-of-flight technique for measuring the mobility of photoexcited charge carriers in certain crystals exhibiting the electro-optic effect. We used this holographic technique to find that the mobility of photoexcited electrons in a previously well-characterized sample of n-type Bi12SiO20 is 0.240.07 cm2 V-1 s-1, independent of electric field in our range of observation (2002000 V/cm). We also present results of transient photocurrent measurements. When used with our absorption measurement and previously reported values of the quantum efficiency and mobility-lifetime product, they give two independent estimates of electron mobility that are consistent with our directly measured value.