ATOMIC-STRUCTURE OF SI SURFACES ETCHED IN TRITON NAOH SOLUTIONS/

In situ real-time scanning tunneling microscopy is used to study Si et ching in alkaline solutions modified by addition of Triton, a commonly used nonionic surfactant. On Si(111), time sequences of images, with the resolution of-atomic steps, show that the rate of the nucleation o f etch pits is decreased on terraces which reduces the etch rate. Resu lts are interpreted in term of formation of a self-assembled micellar layer of Triton molecules whose disorder in the vicinity of atomic sca le defects improves surface order compared to etching in NaOH. This la yer being not bound to the surface, the (1 x 1)-H-terminated Si(111) s urface is always imaged at high resolution. Potential applications of Triton solutions to the preparation of flat surfaces of Si(111) and (1 00) are discussed.