High-resolution optical methods for characterization of polycrystalline GaAs thin films

Two optical characterization techniques capable of high lateral spatial resolution (∼ 1 µm) are described and applied to the investigation of polycrystalline GaAs. The first technique yields the minority-carrier diffusion length and is based on a measurement of the change in photocurrent collected at a semitransparent Schottky barrier as reverse bias is varied. The second involves a measurement of photoluminescence intensity. The methods yield information about grain boundaries and granular properties, are compatible with conducting substrates, are nondestructive, and have potential for rapid data acquisition.