Frequency dependent capacitance spectroscopy using conductive diamond tips on GaAs/Al2O3 junctions

In this work, an unusual low frequency behavior observed in scanning capacitance microscopy/spectroscopy on GaAs/Al2O3 junctions is investigated. Using a two-dimensional simulation, we show that the frequency behavior of the capacitance—voltage curves can be explained through an increased minority carrier concentration at to the GaAs–Al2O3 interface and tip geometry effects on the nanoscale. An analytic approach to estimate the transition frequency between the low frequency and high frequency regime is also given.