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Epitaxial Lateral Overgrowth of GaN
Author(s) -
Beaumont B.,
Vennéguès Ph.,
Gibart P.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200109)227:1<1::aid-pssb1>3.0.co;2-q
Subject(s) - epitaxy , sapphire , materials science , optoelectronics , dislocation , laser linewidth , gallium nitride , photoluminescence , burgers vector , layer (electronics) , optics , nanotechnology , physics , composite material , laser
Since there is no GaN bulk single crystal available, the whole technological development of GaN based devices relies on heteroepitaxy. Numerous defects are generated in the heteroepitaxy of GaN on sapphire or 6H‐SiC, mainly threading dislocations (TDs). Three types of TDs are currently observed, a type (with Burgers vector 1/3〈 $11 \bar{2}0$ 〉); c type (with 〈0001〉) and mixed a + c (1/3〈 $11 \bar{2}3$ 〉). The Epitaxial Lateral Overgrowth (ELO) technology produces high quality GaN with TD densities in the mid 10 6 cm —2 , linewidth of the low‐temperature photoluminescence (PL) near‐bandgap recombination peaks <1 meV and deep electron traps reduced below 10 14 cm —3 (compared to mid 10 15 cm —3 in standard GaN). Numerous modifications of the ELO process have been proposed in order either to avoid technological steps (mask‐less ELO) or to improve it (pendeo‐epitaxy). Basically developed on either sapphire or 6H‐SiC, the ELO technology is also achievable on (111)Si or (111)3C‐SiC/Si provided that an appropriate buffer layer is grown to avoid cracks. More sophisticated technologies have been implemented to further increase the useable part of the ELO GaN surface (two technological steps, three‐step ELO). Unfortunately, in‐depth understanding of the basic ELO process is still missing, i.e. of the growth anisotropy and bending of dislocations.