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Measurements of strain in AlGaN/GaN HEMT structures grown by plasma assisted molecular beam epitaxy

Jolanta Borysiuk 1Kamil Sobczak 1Aleksandra Wierzbicka 1Kamil Klosek 1Marta Sobanska 1Zbigniew R. Zytkiewicz 1Boleslaw L. Lucznik 2

1. Institute of Physics, Polish Academy of Sciences, Warsaw 02-668, Poland
2. Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland

The AlGaN/GaN high electron mobility transistor (HEMT) structures were grown on the (0001) HVPE bulk GaN substrates using plasma-assisted molecular-beam epitaxy (PAMBE). The AlGaN layers of content of 12% or 20% were grown to nominal 20nm thickness and the 3nm thick GaN cap was added. High-resolution X-ray diffraction (HRXRD) measurements were used to determine crystallographic quality of HEMT structures. Built-in strain was obtained from peak intensity analysis. An effective lattice constant was derived from the shifts of the peaks positions. These X-ray data were compared to local measurements performed by transmission electron microscopy (TEM) – Fig.1. Tetragonal distortion was used for lattice strain in the interface regions. Structure geometry was also obtained from TEM images. Overall quality of the structures and their performance was assessed.
     Figure 1. TEM image of HEMT structure.

Figure 2.  XRD map of the (11 4) reflection.


This work was partially supported by the European Union within European Regional Development Found, through grant Innovative Economy POIG.01.01.02-00-008/08 NanoBiom. One of the authors (JB) wishes to thank the National Science Centre (Poland) support by grant DEC-2011/03/B/ST5/02698.

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Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 5, by Jolanta Borysiuk
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-15 19:04
Revised:   2013-07-26 09:03