Chemically cleaned InP(100) surfaces in aqueous HF solutions

Chemically cleaned InP(100) surfaces in aqueous HF solutions at 20 degrees C have been studied using X-ray photoelectron spectroscopy (XPS) spectrosco pic ellipsometry (SE), atomic force microscopy (AFM) and contact-angle meas urements. The XPS data clearly indicated that the solutions caused the remo val of the native oxide and left behind InP surface terminated by atomic fl uorine. The SE data also indicated the immediate removal of the native oxid e upon immersing the sample in the solutions. The AFM rms roughnesses for t he HF-cleaned surfaces were similar to 0.1-0.2 nm which were considerably s maller than those obtained from the SE data (similar to 0.6 nm), the differ ence may be due to the SE technique being sensitive to both the surface mic roroughness and adsorbed chemical species (and/or a newly grown oxide film) , while AFM was sensitive only to the surface microroughness. The as-degrea sed InP surface was, if anything, hydrophilic, while the HF-cleaned surface s were hydrophobic. (C) 2000 Elsevier Science S.A. All rights reserved.