Brush Layers of Bioinspired Polypeptoids for Deterministic Doping of Semiconductors

Monodisperse polypeptoids with 5, 10, 14, and 19 monomer units and a phosphorus containing moiety at one end were prepared through the submonomer solid-phase synthetic approach. The insertion of defects at specific positions along the polymer chain enables the suppression of their crystallinity thus leading to amorphous samples with improved solubility. Polypeptoid brushes were prepared by performing the “grafting to” process at high temperature for a short time thus decoupling the grafting process from thermal degradation. Precise control of the brush thickness is achieved by selection of the polypeptoid chain length. Ashing the polypeptoid brushes by O2 plasma leads to complete removal of the chains while preserving the dopant atoms covalently bound to the silicon surface. In this way, phosphorus δ-layers with precisely predetermined amounts of dopant atoms are obtained. These results highlight the possibility to integrate precision polymers prepared by perfectly reproducible procedures in the sophisticated processes of the microelectronics industry.