HVPE Nitrides

Gallium nitride (GaN) substrates are highly needed for the fabrication of high-quality electronic and optoelectronic devices such as blue laser diodes with high reliability and white or UV LEDs with high efficiency. Up to now, the growth of GaN crystals from melt of sufficiently large size has not been achieved as it is common e.g. for GaAs substrates.

The HVPE technique is currently accepted worldwide to be one of the promising techniques for this purpose. It allows for large-size crystal growth with rates exceeding 100 µm/h. This technique uses liquid gallium which is transported to the substrate after being transformed into gallium chloride by reaction with hydrogen chloride at temperatures of about 900°C. On the substrate gallium nitride is formed by reaction of gallium chloride and ammonia at temperatures of about 1050°C.

A single wafer Aixtron HVPE horizontal reactor is used for basic investigation of growth processes. A vertical Aixtron HVPE reactor is dedicated to the growth of GaN bulk crystals which are then processed into GaN substrates by FBH's industrial partner Freiberger Compound Materials GmbH. Both reactors are equipped with in-situ reflectometers of type LayTec EpiR for optimization of growth parameters.