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Optimization of homoepitaxially grown AlGaN/GaN heterostructures
Author(s) -
Grenko J. A.,
Ebert C. W.,
Reynolds C. L.,
Duscher G. J.,
Barlage D. W.,
Johnson M. A. L.,
Preble E. A.,
Paskova T.,
Evans K. R.
Publication year - 2010
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200925508
Subject(s) - heterojunction , metalorganic vapour phase epitaxy , materials science , epitaxy , fermi gas , sapphire , optoelectronics , doping , electron mobility , layer (electronics) , condensed matter physics , electron , nanotechnology , physics , optics , laser , quantum mechanics
We report on the growth of Al 0.25 Ga 0.75 N/GaN heterostructures on low dislocation density semi‐insulating c ‐axis GaN substrates by metalorganic vapor phase epitaxy (MOVPE). A room temperature (RT) Hall mobility ( µ RT ) up to 2065 cm 2 V −1 s −1 at sheet density ( n s ) of 8.25 × 10 12 cm −2 has been measured. This work compliments prior studies in which we observed a buffer‐induced modulation of the RT two‐dimensional electron gas (2DEG) n s and µ RT by varying the GaN buffer layer thickness. Here, we focus on the optimization of the heterostructure 2DEG properties by elimination of silicon doping in the Al 0.25 Ga 0.75 N barrier and unintentional Al in the not‐intentionally doped (n.i.d.) GaN buffer layer. The 15% improvement in µ RT and n s relative to previous results is consistent with those predicted by Poisson solver calculations. Use of thick GaN buffers has minimized the theoretical mobility reduction based on intersubband scattering and has enabled us to determine the 2DEG sheet density associated with the polarization field ( $n_{{\rm s}}^{{\rm polar}} $ ) to be ∼5 × 10 12 cm −2 .