Wa. Doolittle et al., GROWTH OF GAN ON LITHIUM GALLATE SUBSTRATES FOR DEVELOPMENT OF A GAN THIN COMPLIANT SUBSTRATE, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 16(3), 1998, pp. 1300-1304
Since we have found that an entire substrate can be chemically removed
in less than 5 min and since GaN is impervious to chemical etching, t
he GaN on lithium gallate (LGO) system is an excellent template (due t
o near infinite etch selectivity) for developing a thin film/compliant
GaN substrate. Here we report on our efforts to grow GaN on LGO, incl
uding improvement of the atomic surface morphology using pregrowth pre
treatments. We also report the first transferred thin film GaN substra
te grown on LGO, transferred off of LGO and mounted on GaAs. With this
approach, (InAl)GaN alloys can be grown on thin GaN films, implementi
ng a ''compliant'' substrate for the nitride alloy system. In addition
, the flexibility of bonding to low cost Si, metal or standard ceramic
IC packages is an attractive alternative to SiC and hydride vapor pha
se epitaxy GaN substrates for optimizing cost verses thermal conductiv
ity concerns. We have demonstrated high quality growth of GaN on LGO.
X-ray rocking curves of 145 arcsec are shown on a 0.28 mu m thick film
s. For the first time, we present data on the out-of-plane crystalline
quality of GaN/LGO material. Likewise, we show two orders of magnitud
e improvement in residual doping concentration and factors of 4 improv
ement in electron mobility. We show substantial vendor to vendor and i
ntravendor LGO material quality variations. We have quantified the des
orption of Ga and Li from the surface of LGO at typical growth tempera
tures using in situ desorption mass spectroscopy and x-ray photoelectr
on spectroscopy. (C) 1998 American Vaccum Society.