Epi-Gd2O3/AlGaN/GaN MOS HEMT on 150 mm Si wafer: A fully epitaxial system for high power application

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Applied Physics Letters, Volume 115, issue 6
In this letter, we report the impact of epitaxial Gd2O3 on the electrical properties of an AlGaN/GaN high electron mobility transistor (HEMT) grown on a 150 mm diameter Si (111) substrate. Incorporation of epitaxial Gd2O3 grown by the molecular beam epitaxy technique under a metal gate (metal/Gd2O3/AlGaN/GaN) causes six orders of magnitude reduction in gate leakage current compared to metal/AlGaN/GaN HEMT. We observe that epi-Gd2O3 undergoes complete structural changes from hexagonal to monoclinic as the thickness of the layer is increased from 2.8 nm to 15 nm. Such structural transformation is found to have a strong impact on electrical properties whereby the gate leakage current reaches its minimum value when the oxide thickness is 2.8 nm. We find a similar trend in the density of interface traps (Dit) having a minimum value of 2.98 × 1012 cm-2 eV-1 for the epioxide layer of thickness 2.8 nm. Our measurements also confirm a significant increase in the two dimensional electron gas (2DEG) density (∼40%) at AlGaN/GaN interface with epioxide grown on AlGaN, thus confirming the contribution of epitaxial lattice strain on 2DEG modulation.
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Sarkar , R , Bhunia , S , Nag , D , Barik , B C , Das Gupta , K , Saha , D , Ganguly , S , Laha , A , Lemettinen , J , Kauppinen , C , Kim , I , Suihkonen , S , Gribisch , P & Osten , H J 2019 , ' Epi-Gd 2 O 3 /AlGaN/GaN MOS HEMT on 150 mm Si wafer: A fully epitaxial system for high power application ' , Applied Physics Letters , vol. 115 , no. 6 , 063502 . https://doi.org/10.1063/1.5109861