Vertical leakage mechanism in GaN on Si high electron mobility transistor buffer layers
Control of leakage currents in the buffer layers of GaN based transistors on Si substrates is vital for the demonstration of high performance devices. Here, we show that the growth conditions during the metal organic chemical vapour deposition growth of the graded AlGaN strain relief layers (SRLs) c...
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Veröffentlicht in: | Journal of applied physics 2018-08, Vol.124 (5) |
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Hauptverfasser: | , , , , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Control of leakage currents in the buffer layers of GaN based transistors on Si
substrates is vital for the demonstration of high performance devices. Here, we show that
the growth conditions during the metal organic chemical vapour deposition growth of the
graded AlGaN strain relief layers (SRLs) can significantly influence the vertical leakage.
Using scanning capacitance microscopy, secondary ion mass spectrometry, and transmission
electron microscopy, we investigate the origins of leakage paths and show that they result
from the preferential incorporation of oxygen impurities on the side wall facets of the
inverted hexagonal pyramidal pits which can occur during the growth of the graded AlGaN
SRL. We also show that when 2D growth of the AlGaN SRL is maintained a significant
increase in the breakdown voltage can be achieved even in much thinner buffer layer
structures. These results demonstrate the importance of controlling the morphology of the
high electron mobility transistor buffer layer as even at a very low density the leakage
paths identified would provide leakage paths in large area devices. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.5027680 |