Characterisation of GaN crystals and epilayers grown from a solution at room pressure

GaN crystals were synthesised in a horizontal reactor system using ammonia as a nitrogen source. In the first part of this project a parameter study was performed to evaluate a suitable growth window, concerning e.g. process temperature, gas flows or partial pressures of the process gases. These first experiments were carried out in a horizontal reactor with a silica ampoule using a quartz crucible. Applying the optimum parameter set it was possible to grow GaN single crystals and free-standing GaN with a thickness of 0.1 mm. Pure hexagonal GaN was confirmed by XRD and EDX measurements, neither a cubic phase content nor any other binary or ternary phase was found, which is in agreement with the Raman spectroscopy data and the results from cathodoluminescence and PL measurements. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)