One-step growth of ca. 2-15 nm polymer thin films on hydrogen-terminated silicon

Here we show direct polymer growth on hydrogen-terminated silicon (Si-H) as a one-step process. Si-H is immersed in a heated solution of an initiator, a monomer, and a crosslinker. The resulting polymer films are 2-15 nm thick, the thickness can be tuned by varying reaction conditions, and the polymer films are robust. Thinner films are obtained in polymer growth without crosslinker. Radicals produced by the initiator and in growing polymer chains may pluck H atoms from Si-H to make reactive dangling bonds. These in turn appear to react with monomers and crosslinkers. Crosslinkers tethered through one double bond may be grafted into polymer chains growing in solution. Surface reactivity is demonstrated by optical ellipsometry, X-ray photoelectron spectroscopy, atomic force microscopy, and wetting.