7 December 1993 Thickness uniformity requirements for GaAs/AlGaAs miniband transport quantum-well infrared detector wafers
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Abstract
Large-area GaAs/AlGaAs quantum-well IR detector arrays need highly uniform layer thicknesses to meet response wavelength uniformity requirements. We have measured the variation in absorption wavelength with layer thickness in a miniband transport (MBT) IR detector consisting of multiple periods of doped quantum wells with superlattice barriers. The absorption wavelength and quantum well width were determined in samples taken from the radius of a detector wafer. A model was developed to fit the wavelength versus well width data from the grown wafer. For small changes in well width the wavelength varies linearly with well width. The MBT IR detector structure grown for this experiment had a slope of 0.11 micrometers /angstroms, corresponding to a thickness deviation of 0.6% for a wavelength deviation of 0.05 micrometers . The model can be used to design other MBT IR detectors with slightly higher thickness tolerances. A uniformity test structure was developed for tracking layer thickness and composition variations over epitaxial wafers. Examples of typical molecular beam epitaxy (MBE) uniformities from a single- and a multiwafer MBE are presented.
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Fredrick J. Towner, Fredrick J. Towner, S. P. Svensson, S. P. Svensson, John W. Little, John W. Little, William A. Beck, William A. Beck, } "Thickness uniformity requirements for GaAs/AlGaAs miniband transport quantum-well infrared detector wafers", Proc. SPIE 2021, Growth and Characterization of Materials for Infrared Detectors, (7 December 1993); doi: 10.1117/12.164939; https://doi.org/10.1117/12.164939
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