We have unpinned the Fermi level at the surface of both n- and p-type (100) GaAs in air. Light-induced photochemistry between GaAs and water unpins the surface Fermi level by reducing the surface state density. Excitation photoluminescence spectroscopy shows a substantial decrease in both surface band bending and surface recombination velocity in treated samples, consistent with a greatly reduced surface state density (≂1011 cm−2). Capacitance-voltage measurements on metal-insulator-semiconductor structures corroborate this reduction in surface state density and show that the band bending may be controlled externally, indicating an unpinned Fermi level at the insulator/GaAs interface. We discuss a possible unpinning mechanism.
One of the major motivations for using computerized waveform capture for deep-level transient spectroscopy is the capability to employ methods of analysis more accurate and informative than boxcars and correlators. Accordingly, we have adapted the fast Fourier transform method and the method of moments to analyze single and multiple exponential decays, respectively. We present relevant details of our experimental system, and compare the boxcar method with the new analyses on both simulated and experimental data. The new analyses have given conclusive, accurate results in cases where the boxcar is ambiguous or directly misleading.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.