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Temperature mapping of Al0.85In0.15N/AlN/GaN high electron mobility transistors through micro-photoluminescence studies
Published online by Cambridge University Press: 20 May 2009
Abstract
Crack-free lattice-matched Al0.85In0.15N/GaN heterostructures were grown on sapphire substrates with barrier thicknesses up to 100 nm which exhibit very high polarization-induced electron sheet density (${>}2.5\times 10^{13}$ cm−2) located at the heterointerface. These layers have been further processed as high electron mobility transistors (HEMTs). Optical characterization of these structures was carried out by photoluminescence and microphotoluminescence (${\rm \mu} $PL) for different biased voltages. The insertion of an InGaN back-barrier unambiguously reveals that spatially direct optical recombinations occur within the AlInN alloy. Since the GaN excitonic bandgap is very sensitive to local temperature changes, the ${\rm \mu} $PL technique allows mapping very precisely the actual local temperature distribution in biased HEMT devices. For a gate length of 1.5 ${\rm \mu }$m temperatures up to 1130 K were found at a drain-source voltage of 20 V thus indicating the presence of a hot phonon bath.
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- © EDP Sciences, 2009
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