9319987 Yang The proposal program stresses the importance of understanding practical device interfaces by making use of both surface spectroscopies and electrical measurements. The chemical nature of the semiconductor surface and interfaces will be studied with X-ray photemission spectroscopy (XPS). In addition, we plan to use Auger electron spectroscopy (AES) to assess the issues of stoichiometry and interface segregation. These spectroscopic results will be corroborated by current-voltage (I-V), current gain, capacitance-voltage (C-V) and contact resistance measurements. The data of XPS and AES will be used as sign-posts giving us the insight and direction to overcome an existing material difficulty and improve the device performance. Specific problems to be addressed include GaAs surface passivation, SiGe oxidation and non-alloyed ohmic contact formation. ***