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Title
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Comparison of As- and P-based metamorphic buffers for high performance InP heterojunction bipolar transistor and high electron mobility transistor applications
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Author
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Abstract
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| Metamorphic buffers (M-buffers) consisting of graded InAlAs or bulk InP were employed for the production of InP-based epiwafers on GaAs substrates by molecular-beam epitaxy. The graded InAlAs is the standard for production metamorphic high electron mobility transistors (M-HEMTs), while the bulk InP offers superior thermal properties for higher current density circuits. The surface morphology and crystal structure of the two M-buffers showed different relaxation mechanisms. The graded InAlAs gave a cross-hatched pattern with nearly full relaxation and very effective dislocation filtering, while the bulk InP had a uniform isotropic surface with dislocations propagating further up towards the active layers. Both types of M-buffers had atomic force microscopy root-mean-square roughness values around 2030 Å. The Hall transport properties of high electron mobility transistors (HEMTs) grown on the InAlAs M-buffer, and a baseline HEMT grown lattice matched on InP, both had room-temperature mobilities >10 000 cm2/V s, while the M-HEMT on the InP M-buffer showed a decrease to 9000 cm2/V s. Similarly, the dc parameters of a double heterojunction bipolar transistor (DHBT) grown on the InAlAs M-buffer were much closer to the baseline heterojunction bipolar transistor than a DHBT grown on the InP M-buffer. A high breakdown voltage of 11.3 V was achieved on an M-DHBT with the InAlAs M-buffer. We speculate that the degradation in device characteristics on the InP M-buffer was related to the incomplete dislocation filtering. |
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Language
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English
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Source (journal)
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Journal of vacuum science & technology. B. Microelectronics and nanometer structures. Processing, measurement and phenomena. - Woodbury, N.Y.
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Publication
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Woodbury, N.Y.
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2004
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ISSN
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1071-1023
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DOI
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10.1116/1.1691412
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Volume/pages
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22
:3
(2004)
, p. 1565-1569
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ISI
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000222481400141
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Full text (Publisher's DOI)
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