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Effect of Buffer Design on AlGaN/AlN/GaN Heterostrucutres by MBE

Published online by Cambridge University Press:  01 February 2011

Gon Namkoong
Affiliation:
Doolittle Georgia Institute of Technology, Microelectronic Research Center, 791 Atlantic Dr, Atlanta, GA, USA
W. Alan
Affiliation:
Doolittle Georgia Institute of Technology, Microelectronic Research Center, 791 Atlantic Dr, Atlanta, GA, USA
A. S. Brown
Affiliation:
Department of Electrical and Computer Engineering, Duke University, Durham, NC 27709, USA
M. Losurdo
Affiliation:
Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM, via Orabona 4 –70126 Bari, Italy
M. M. Giangregorio
Affiliation:
Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM, via Orabona 4 –70126 Bari, Italy
G. Bruno
Affiliation:
Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM, via Orabona 4 –70126 Bari, Italy
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Abstract

The effect of the buffer layers on the subsequent GaN epitaxial layers and electrical properties of AlGaN/AlN/GaN heterojunction structures nitrided at various temperatures was investigated. For AlN buffer layers, two different growth conditions of AlN buffer layers were introduced to avoid Al droplets. We found that etch pit density and structural quality of GaN epitaxial layer strongly depends on the growth conditions of AlN buffer layers. When using a double buffer layer (low temperature GaN on high temperature AlN) for 200 °C nitridation, the etch pit density was measured to high 107 cm-2 in GaN epitaxial layers. Furthermore, we observed that electrical properties of AlGaN/AlN/GaN heterostructures depend on growth conditions of buffer layers and nitridation temperatures. The mobility in Al0.33Ga0.67N/AlN/GaN structures grown on single AlN buffer layers for 200 °C nitridation were 1300 cm2/Vs at a sheet charge of 1.6×1013 cm-2. Using the double buffer layer for 200 °C nitridation, the mobility increased to 1587 cm2/Vs with a sheet charge of 1.25×1013 cm-2.

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articles
Copyright
Copyright © Materials Research Society 2004

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References

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