Metalorganic Chemical Vapor Deposition Growth of High-Quality InAs/GaSb Type II Superlattices for Mid-IR Photodetector Applications
X. B. Zhang , A. Petschke, S. Mou , C. Xu , J. H. Ryou , S. L. Chuang , K. C. Hsieh, and R. D. Dupuis 1) Center for Compound Semiconductors and School of Electrical and Computer Engineering, Georgia Institute of Technology, 777 Atlantic Drive NW, Atlanta, GA, 30332-0250, USA 2) Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801, USA
Metal organic chemical vapor deposition of metaphorphic InAs GaSb superlattices on (0 0 1) GaAs substrates for mid-IR photodetector applications
Abstract InAs/GaSb superlattices (SLs) were grown on (0 0 1) GaAs substrates by metal organic chemical vapor deposition. A thin low temperature (LT) GaSb nucleation layer followed by a 250 nm thick high temperature (HT) GaSb buffer layer were introduced before the growth of the SLs and their growth conditions were optimized. The effects of growth temperature and GaSb growth rate on the morphology and structural properties of the SL were systematically studied. Atomic force microscopy, photoluminescence, transmission electron microscopy and X-ray diffraction were used to characterize the grown structures. Generally, nanopipes, about 100 nm in diameter, were found in the grown structures and their formation depends strongly on the growth temperature and the GaSb growth rate in growing the SL. By optimizing these parameters, high-quality InAs/GaSb SLs without nanopipes and with sharp interfaces have been realized.
Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel
The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.