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|Author(s):||Seong-Eun Park; Joseph J. Kopanski; Youn-Seon Kang; Lawrence H. Robins; Hyun-Keel Shin;|
|Title:||Determination of surface barrier height and surface state density in GaN films grown on sapphire substrates|
|Published:||March 24, 2005|
|Abstract:||Photoreflectance (PR) modulation spectroscopy was performed to investigate surface properties of GaN films grown on sapphire substrates. From the period of the Franz-Keldysh oscillations, the surface electric field across the GaN space charge region was found to be (197.3 '' 11.4) kV/cm, which corresponds to a surface state density of 1.0 x 10e12 cm^-2. A surface barrier height (SBH) of 0.71 eV was determined by fitting the dependence of the PR intensities on pump beam power density. We suggest that a deep level is formed at 2.68 eV above the GaN valence band edge due to the large density of surface states.|
|Proceedings:||MRS Electronic Proceedings|
|Pages:||pp. E3.2.1 - E3.2.6|
|Dates:||November 29-December 3, 2004|
|Keywords:||GaN,Photoreflectance,Surface electronic properties|