Effects of trimethylindium on the purity of In0.5Al0.5P and In0.5Al0.5as epilayers grown by metalorganic chemical vapor deposition |
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Authors: | J C Chen Z C Huang K J Lee Ravi Kanjolia |
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Affiliation: | (1) Department of Computer Science and Electrical Engineering, University of Maryland Baltimore County, 21228 Baltimore, MD;(2) Morton International, Inc., 01923 Danvers, MA;(3) Hughes-STX Corporation, 7701 Greenbelt Road, Suite 400, 20770 Greenbelt, MD;(4) Department of Electrical Engineering, University of Maryland, College Park, College Park, 20742, MD |
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Abstract: | In0.5Al0.5P lattice-matched to GaAs and In0.5A10.5As lattice-matched to InP epilayers were grown by atmospheric pressure metalorganic chemical vapor deposition (AP-MOCVD).
The effect of trimethylindium on the purity of the as-grown layers was systematically studied using secondary ion mass spectroscopy
(SIMS), deep level transient spectroscopy (DLTS), and capacitance-voltage (C-V) measurements. The SIMS results showed that
oxygen is the main impurity in all layers and the oxygen concentration in InAlP was approximately one to four orders of magnitude
higher than the oxygen concentration found in InALAs when the same indium source was used, indicating that more oxygen was
introduced by the phosphine source than by the arsine source. Two electron traps in the InAlP epilayers and four electron
traps in the InALAs epilayers were observed in this study. When a high-purity indium source was used, the best InAlP epilayer
showed only one deep electron trap at 0.50 eV while the best InALAs epilayer showed no deep levels measured by DLTS. In addition,
we also found that a high concentration of oxygen is related to the high resistivity in both material systems; this suggests
that semi-insulating (SI) materials can be achieved by oxygen doping and high quality conducting materials can only be obtained
through the reduction of oxygen. The oxygen concentration measured by SIMS in the best InALAs epilayer was as low as 3 × 1017 cm−3. |
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Keywords: | InAlP InALAs metalorganic chemical vapor deposition (MOCVD) trimethylindium (TMIn) |
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