Study of SiO2Si interfaces by photocurrent measurements

A Novel Method for the Simultaneous Characterization of Bulk Impurities and Surface States by Photocurrent Measurements

“…A specific experiment was set up in order to accurately measure the ratio I* 0 /I 0 . 7,9 Relatively thick oxides (200 Å) were grown, the oxide at wafer back side was stripped and the back-side photocurrent was measured with the front-side surface exposed to air (measurement of I* BPC ). Then samples were immersed in the HF solution and I BPC was measured immediately, before the oxide could be etched by the HF solution.…”

“…Bulk and surface recombination contributions were shown to be effectively separated by photocurrent measurements [4][5][6][7][8][9] in the Elymat technique. In this technique, 10 minority carriers are injected by a laser beam at wafer front side and collected by a silicon-electrolyte junction that behaves like a Schottky contact at wafer back side.…”

Surface Recombination Velocity from Photocurrent Measurements: Validation and Applications

“…To this aim, photocurrent is measured under different conditions of surface passivation, 14 thus providing detailed maps of surface recombination as well as carrier lifetime. A recent test of this method 7 showed that the data for surface recombination velocity so obtained depend as expected on process conditions (oxidation cycle, hydrogen annealing) and that good sensitivity is obtained (surface recombination velocities of the order of a few tens of centimeters per second can be evaluated). However, at present no experimental results are available relating these data for surface recombination velocity to surface-state density, as obtained, for instance, from measurements of capacitance vs. voltage in suitably prepared capacitors.…”

“…For these reasons, the extension of these techniques to the study of surface properties is actively studied. [6][7][8][9][10] Photocurrent measurements have been used for a long time for the determination of bulk lifetime and surface recombination velocity, 11 for instance in the optical-beam-induced-current (OBIC) technique. 12,13 For what concerns bulk properties, photocurrent measurements have been commonly used for some years in the Elymat technique (electrolytic metal tracer, Ref.…”

“…With respect to other OBIC techniques, the Elymat technique has the peculiarity that it uses electrolyte contacts to wafer surfaces and that the injecting beam can be scanned over the entire wafer surface, thus providing maps of carrier recombination lifetime. More recently, it was shown that the Elymat technique 6,7 can be used for the evaluation of surface recombination velocity, in addition to bulk recombination lifetime. To this aim, photocurrent is measured under different conditions of surface passivation, 14 thus providing detailed maps of surface recombination as well as carrier lifetime.…”