Chemically cleaned InP(100) surfaces in aqueous HF solutions

Chemically cleaned InP(100) surfaces in aqueous HF solutions at 20°C have been studied using X-ray photoelectron spectroscopy (XPS) spectroscopic ellipsometry (SE), atomic force microscopy (AFM) and contact-angle measurements. The XPS data clearly indicated that the solutions caused the removal of the native oxide and left behind InP surface terminated by atomic fluorine. The SE data also indicated the immediate removal of the native oxide upon immersing the sample in the solutions. The AFM rms roughnesses for the HF-cleaned surfaces were ∼0.1–0.2 nm which were considerably smaller than those obtained from the SE data (∼0.6 nm), the difference may be due to the SE technique being sensitive to both the surface microroughness and adsorbed chemical species (and/or a newly grown oxide film), while AFM was sensitive only to the surface microroughness. The as-degreased InP surface was, if anything, hydrophilic, while the HF-cleaned surfaces were hydrophobic.