Donovan L. Barrett
II-VI Incorporated
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Featured researches published by Donovan L. Barrett.
Materials Science Forum | 2004
Thomas E. Anderson; Donovan L. Barrett; J. Chen; W.T. Elkington; Ejiro Emorhokpor; Avinash K. Gupta; Cheyenne Johnson; R.H. Hopkins; Charles Martin; Thomas Kerr; Edward Semenas; Andrew E. Souzis; Charles D. Tanner; Murugesu Yoganathan; Ilya Zwieback
Abstract. The Wide Bandgap Materials Group of II-VI Inc., develops, manufactures and markets n+ and semi-insulating (SI) 6H SiC crystals, including vanadium-compensated and V-free. The PVT growth process is tuned to produce high-quality semi-insulating 6H SiC boules with micropipe densities below 15 cm (for 2-inch wafers) and below 70 cm (for 3-inch wafers). Room temperature resistivity for 2-inch and 3-inch SI V-doped wafers is greater than 10 Ω·cm and 10 Ω·cm, respectively. A novel synthesis process is used for the production of high-purity polycrystalline SiC source, yielding a material in which most impurities are below their GDMS detection limits. An advanced PVT process (APVT) has been developed for the growth of V-free SI 6H SiC crystals. These APVT SiC crystals contain boron below 6.2·10cm, nitrogen below 4.0·10cm and demonstrate semi-insulating behavior with ρ between 10 and 10 Ω·cm. Photoluminescence and EPR of V-free 6H SiC has been studied and EPR data have been assigned to native point defects (C vacancy, Si antisite and CVAC-CSi pair).
Materials Science Forum | 2005
Thomas E. Anderson; Donovan L. Barrett; J. Chen; Ejiro Emorhokpor; Avinash K. Gupta; R.H. Hopkins; Andrew E. Souzis; Charles D. Tanner; Murugesu Yoganathan; Ilya Zwieback
II-VI has developed an Advanced PVT (APVT) process for the growth of nominally undoped (vanadium-free) semi-insulating 2” and 3” diameter 6H-SiC crystals with room temperature resistivity up to 1010 W·cm. The process utilizes high-purity SiC source and employs special measures aimed at the reduction of the impurity background. The APVT-grown material demonstrates concentrations of B and N reduced to about 2·1015cm-3. Wafer resistivity has been studied and correlated with Schottky barrier capacitance, yielding the density of deep compensating centers in 6H-SiC in the low 1015 cm-3 range for both ntype and p-type material. The nearly equal density of deep donors and deep acceptors ndicates that the centers responsible for the intrinsic compensation can be amphoteric. TheEPR density of spins from free carbon vacancies is about 1014 cm-3. It is also hypothesized that impurity-vacancy complexes can be present in the undoped material and participate in compensation.
Materials Science Forum | 2005
Thomas E. Anderson; Donovan L. Barrett; J. Chen; Ejiro Emorhokpor; Avinash K. Gupta; R.H. Hopkins; Andrew E. Souzis; Charles D. Tanner; Murugesu Yoganathan; Ilya Zwieback; W. J. Choyke; Robert P. Devaty; Fei Yan
Semi-insulating 6H SiC substrates, 2”, 3” and 100mm in diameter, and n+ 4H SiC substrates, 2” and 3” in diameter, are grown at II-VI using the Advanced Physical Vapor Transport (APVT) technique [1]. The process utilizes high-purity SiC source and employs special measures aimed at the reduction of background contamination. Semi-insulating properties are achieved by precise vanadium compensation, which yields substrates with stable and uniform electrical resistivity reaching ~ 1011 Ω-cm and higher. Conductive n+ 4H SiC crystals with the spatially uniform resistivity of 0.02 W-cm are grown using nitrogen doping. Crystal quality of the substrates, their electrical properties and low temperature photoluminescence are discussed.
Archive | 1993
Donovan L. Barrett; H.M. Hobgood; James P. McHugh; R.H. Hopkins
Archive | 2005
J. Chen; Ilya Zwieback; Avinash K. Gupta; Donovan L. Barrett; R.H. Hopkins; Edward Semenas; Thomas A. Anderson; Andrew E. Souzis
Archive | 1995
Donovan L. Barrett; Raymond G. Seidensticker; R.H. Hopkins
Archive | 1995
Donovan L. Barrett; R.N. Thomas; Raymond G. Seidensticker; R.H. Hopkins
Archive | 1997
Donovan L. Barrett; Raymond G. Seidensticker; R.H. Hopkins
Archive | 2006
Avinash K. Gupta; Edward Semenas; Ilya Zwieback; Donovan L. Barrett; Andrew E. Souzis
Archive | 2013
Ilya Zwieback; Avinash K. Gupta; Ping Wu; Donovan L. Barrett; Gary E. Ruland; Thomas E. Anderson