Covalent Functionalization of GaP(110) Surfaces via a Staudinger-Type Reaction with Perfluorophenyl Azide

Despite the markedly low chemical reactivity of the nonpolar (110) surfaces of III–V semiconductors, the covalent functionalization of GaP(110) surfaces with perfluorophenyl azide (PFPA) molecules by a Staudinger-type reaction occurs only slightly above room temperature (325 K). Scanning tunneling microscopy observations, combined with density functional theory calculations, support the formation of stable, covalent perfluorophenyl nitride (PFPN) molecule–surface bonds, which can be described as Lewis acidic Ga-stabilized phosphine imides. π–π stacking between aromatic, electron-deficient PFPN units results in compact, commensurate 2D molecular assembly at the surface. PFPA deposition on GaP(110) at room temperature with no additional annealing leads to an intermediate phase consistent with an alternating 1D array of physisorbed and chemisorbed molecular units. This work provides a new route for covalently bonding molecular linkages to the (110) surfaces of III–V semiconductors.