Expanding the functionality of electronic materials is often reliant on the attachment of organic molecules to the surface. In this study, several methods for passivating the surface of semipolar (10-1-1) GaN with different chemistries were examined; this included simple physisorption, in-situ functionalization using phosphonic acids, and a two-step carboxylic acid attachment with a peroxide pretreatment. The binding of a variety of different organic adsorbates on semipolar substrates was quantified using X-ray photoelectron spectroscopy (XPS). Our results confirm binding at the organic-inorganic interface through the presence of amine/amide species on the surface. The wide variety of organic molecules, and their binding to inorganic electronic materials, can be exploited to impart specific functionalities in technologies spanning fields of energy, biomedical science, and chemical sensing.