LIGHT-INDUCED OSCILLATING REACTIONS OF SILICON IN AMMONIUM FLUORIDE SOLUTIONS .1. SIMULTANEOUS PHOTOCURRENT AND EXCESS MICROWAVE REFLECTIVITY MEASUREMENTS

For the first time, simultaneous photocurrent, I(ph), and excess microwave reflectivity, m(w)*, profiles are recorded during the light-induced oscillatory behaviour of n-Si(111) in aqueous ammonium fluoride solutions. Stationary oscillations in I(ph), and m(w)* are complementary to each other with maxima of I(ph) at minima of m(w)* and vice versa. At higher positive potentials, irregular oscillatory behaviour is found and the complementarity of the signals is not fully maintained. For the initial time regime a model is suggested tentatively to determine electronic interface parameters from the simultaneous measurement of I(ph) and m(w)*. For increased time, the oscillatory behaviour has also been evaluated with respect to surface recombination and charge transfer processes. In this time region, however, the application of the model suggested is problematic, as changes in band bending, trapping of charges and space charge layer recombination are not accounted for. For the observed lowest quantum yields > 0.2, it is assumed that the drift velocity is not the limiting factor.