Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results
Journal article, 2015

The creation of a semi insulating (SI) buffer layer in AlGaN/GaN High Electron Mobility Transistor (HEMT) devices is crucial for preventing a current path beneath the two-dimensional electron gas (2DEG). In this investigation, we evaluate the use of a gaseous carbon gas precursor, propane, for creating a SI GaN buffer layer in a HEMT structure. The carbon doped profile, using propane gas, is a two stepped profile with a high carbon doping (1.5 x 10(18) cm(-3)) epitaxial layer closest to the substrate and a lower doped layer (3 x 10(16) cm(-3)) closest to the 2DEG channel. Secondary Ion Mass Spectrometry measurement shows a uniform incorporation versus depth, and no memory effect from carbon doping can be seen. The high carbon doping (1.5 x 10(18) cm(-3)) does not influence the surface morphology, and a roughness root-mean-square value of 0.43 nm is obtained from Atomic Force Microscopy. High resolution X-ray diffraction measurements show very sharp peaks and no structural degradation can be seen related to the heavy carbon doped layer. HEMTs are fabricated and show an extremely low drain induced barrier lowering value of 0.1 mV/V, demonstrating an excellent buffer isolation. The carbon doped GaN buffer layer using propane gas is compared to samples using carbon from the trimethylgallium molecule, showing equally low leakage currents, demonstrating the capability of growing highly resistive buffer layers using a gaseous carbon source.

optimization

hemts

Physics

mocvd

Author

X. Li

Linköping University

Johan Bergsten

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Daniel Nilsson

Linköping University

O. Danielsson

Linköping University

H. Pedersen

Linköping University

Niklas Rorsman

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

E. Janzen

Linköping University

Urban Forsberg

Linköping University

Applied Physics Letters

0003-6951 (ISSN) 1077-3118 (eISSN)

Vol. 107 26 262105

Subject Categories

Materials Chemistry

DOI

10.1063/1.4937575

More information

Latest update

2/28/2018