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High quality GaN boules

FBH research: 14.02.2011

GaN boule

6.3 mm thick GaN boule

Efficient blue-violet laser diodes with high reliability and long device lifetimes require GaN substrates with high material quality at affordable prices. Today, such substrates are produced individually by growth of 0.5 - 1 mm thick layers on a foreign substrate and subsequent removal of the layer from this substrate. This procedure is complicated and costly leading to largely scattering properties of the GaN substrates. As an alternative approach FBH is developing a technology for the growth of thick GaN boules. From such boules a number of substrates of higher quality can then be sliced as commonly applied for silicon and other semiconductors. GaN boules of two inch diameter and lengths exceeding 6 mm are grown at high and thus productive rates of 0.45 mm/h. Low dislocations densities well below 106 cm-2, a high purity and a very high thermal conductivity of 300 W/mK proof the excellent quality of these crystals which is necessary for a number of applications.

Aim of further work is to increase the diameter and boule lengths in order to slice substrates from the boules in cooperation with an industrial partner. N-type crystals shall be developed by doping with silicon while semi-insulating substrates shall be manufactured from boules, doped with iron. This will open new fields of applications for GaN substrates regarding ultra-bright LEDs and fast and efficient power transistors, which are being developed at FBH.

Publications:

E. Richter, U.Zeimer, F. Brunner, S. Hagedorn, M. Weyers, G. Tränkle, "Boule-like growth of GaN by HVPE", Phys. Status Solidi C 7, 28-31 (2010), doi: 10.1002/pssc.200982616.

E. Richter, U. Zeimer, S. Hagedorn, M. Wagner, F. Brunner, M. Weyers, G. Tränkle, "Hydride vapor phase epitaxy of GaN boules using high growth rates", J. Cryst. Growth 312, 2537-2541 (2010), doi:10.1016/j.jcrysgro.2010.04.009.

E. Richter, M. Gründer, B. Schineller, F. Brunner, U. Zeimer, C. Netzel, M. Weyers, G. Tränkle, "GaN boules grown by high rate HVPE", Phys. Status Solidi C, in press.

FBH research: 14.02.2011