A Corbino Disk Apparatus to Measure Hall Mobilities in Amorphous Semiconductors

Abstract

The Corbino disk technique finds a modern application in the measurement of the Hall mobility in amorphous semiconductors. Unlike conventional Hall effect experiments, the technique yields a direct measurement of the mobility and does not depend on a separate measurement of the conductivity. In addition, no voltage contacts are required. The apparatus described here is optimized for the regime of low mobility and high resistivity amorphous semiconductors but also works well on higher conductivity samples. The sensitivity of the apparatus is adequate to routinely measure mobilities to as low as 0.1 cm2/V·sec with a sample current of less than 1 mA at a frequency of 105 Hz and a magnetic field of up to 2 T. Under these conditions, reproducibility errors are less than 5%. Improvement in performance through the use of higher magnetic fields and digital signal averaging is discussed.