Modulation spectroscopy techniques for characterization of device-processing-related issues in GaAs

摘要

For elucidating near-surface defects related to GaAs-based device fabrication/processing, modulation spectroscopy techniques are shown to be quite useful due to their capability of measuring surface field by analyzing the Franz-Keldysh oscillation components. This argument is based on our recent application to two kinds of subjects; dryetching-induced carrier-depletion and trapping states present at the passivation-film/GaAs interfaces. In both cases, a unique feature of i/n- or i/p-GaAs double-layer structure is utilized to realize the optimal characterization scheme for individual pruposes. Electrical information obtained by such an optical approach is discussed in comparison with that by the conventional capacitance methods and several advantages are pointed out.