| AVS 54th International Symposium | |
| Surface Science | Thursday Sessions |
| Session SS2-ThM |
| Session: | Surface Structure of Compound Semiconductors |
| Presenter: | R. Stine, U.S. Naval Research Laboratory |
| Authors: | R. Stine, U.S. Naval Research Laboratory D.Y. Petrovykh, U.S. Naval Research Laboratory and University of Maryland E.H. Aifer, U.S. Naval Research Laboratory L.J. Whitman, U.S. Naval Research Laboratory |
| Correspondent: | Click to Email |
A wide range of III-V semiconductor heterostructure devices are under development for applications in electronics, optoelectronics, and sensing. However, the performance of III-V devices following processing is often detrimentally affected by the formation of mid-bandgap electronic states and the subsequent pinning of the surface Fermi level. Chemical passivation of the device surfaces can stabilize their properties by inhibiting the regrowth of native oxides that can otherwise contribute to Fermi level pinning. Traditionally, this passivation has been accomplished by the formation of surface sulfide groups through wet chemical treatment with an inorganic sulfur-containing compound, such as ammonium sulfide or sodium sulfide. More recently, though, the use of thioacetamide (TAM), an organic sulfur containing compound, has been shown to have a number of advantages over traditional inorganic methods,1-3 including milder reaction conditions and a higher degree of control over the reaction. Although studies have shown the effect of TAM passivation on the electronic properties of devices, little information has been available on the actual chemical reactions that take place at the surfaces. Here, we present detailed X-ray photoelectron spectroscopy (XPS) studies of these surface reactions on gallium antimonide and indium arsenide-important materials for infrared optoelectronics. A comparison of TAM passivation performed under acidic versus basic conditions shows that acidic-TAM treatment produces a thicker sulfide layer that is better suited to the prevention of re-oxidation than that formed under basic-TAM treatment, regardless of exposure time or TAM concentration. We have determined the relative amounts of III-sulfides versus V-sulfides and tracked the rate of re-oxidation for each component independently over time.
1Petrovykh, et al., Appl. Phys. Lett. 86, 242105 (2005)
2Petrovykh, et al., Surf. Interface Anal. 37, 989 (2005)
3Aifer, et al., Proc. SPIE 6542, in press.