ELECTRICAL-PROPERTIES OF N-TYPE (111)SI IN AQUEOUS K4FE(CN)(6) SOLUTION .1. INTERFACE STATES AND RECOMBINATION IMPEDANCE

The properties of n-type (111) Si surfaces in aqueous 0.1 M K4Fe(CN)(6 ) + 0.5 M KCl at pH 9 were studied both in the dark and under illumina tion. In this solution, oxide passivation of the surface gives rise to a variety of electrically active interface states. Both in the dark a nd under illumination, interface states interacting with the conductio n band are present at an energy of about 0.36 eV below the conduction bandedge, giving rise to a characteristic impedance at potentials clos e to the flatband potential. Furthermore, interface states which act a s recombination centers are observed when the surface is illuminated. The density of recombination centers was found to be a function of the light intensity, ranging from 1 x 10(12) to 3 x 10(12) cm(-2), indica ting that these states are related to oxidation intermediates. The rat e constant for recombination was determined to be about 3 x 10(-9) cm( 3) s(-1).