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In-situ Measurement of GaAs Optical Constants and Surface Quality, as Functions of Temperature

Published online by Cambridge University Press:  16 February 2011

Huade Yao
Affiliation:
University of Nebraska, Center for Microelectronic and Optical Materials Research, and Department of Electrical Engineering, Lincoln, NE 68588–0511
Paul G. Snyder
Affiliation:
University of Nebraska, Center for Microelectronic and Optical Materials Research, and Department of Electrical Engineering, Lincoln, NE 68588–0511
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Abstract

In-situ spectroscopic ellipsometry (SE) was applied to monitor GaAs (100) surface changes induced at elevated temperatures inside an ultrahigh vacuum (UHV) chamber (<1×10−9 torr base pressure, without As overpressure). The real time data showed clearly the evolution of the native-oxide desorption at ∼577°C, on a molecular-beam-epitaxy (MBE)-grown GaAs (100) surface. In addition, surface degradation was found before and after the oxide desorption. A clean and smooth surface was obtained from an arsenic-capped, MBE-grown GaAs sample, after the arsenic coating was evaporated at ∼350 °C inside the UHV. Pseudodielectric functions <ε>GaAs, from 1.6 eV to 4.5 eV, were obtained through the SE measurements, from this oxide-free surface, at temperatures ranging from room temperature (RT) to ∼610 °C. These <ε> data were used as reference data to develop an algorithm for determining surface temperatures from in-situ SE measurements, thus turning the SE instrument into a sensitive optical thermometer.

Type
Research Article
Copyright
Copyright © Materials Research Society 1991

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References

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