Maitri Bharatbhai Savani –

Nitride semiconductors, as wide-bandgap semiconductors, playing an increasingly Owing to their wide bandgap characteristics, nitride semiconductors are increasingly important as substrate materials for power electronic devices. Ammonothermal crystal growth is a promising growth method for gallium nitride (GaN). The advantage of this method is the ability to produce crystals with very high structural quality, as well as its scalability. One key parameter of the ammonothermal growth technique is the solubility of GaN in ammonia containing a mineralizer to enhance solubility.

The solubility behavior of GaN in supercritical ammonia is not fully understood given that it depends on several factors, in particular ammonia density, mineralizer concentration, and temperature. Solubility results reported by different research groups vary greatly in the magnitude of solubility and trends are likewise partially inconsistent, although the main influencing factors are similar.

The data reported by different research groups differ in the experimental setup used for the solubility investigations. This includes the autoclave (reactor) as well as the interior components installed inside. Examples are the geometry and the materials of those parts and their surface condition. For liquid ammonia, it is known that its corrosion behavior is influenced by the water content. It is also known that the presence of metals catalytically affects the solubility of ammonia. Considering these aspects, the dissolution of GaN in supercritical ammonia with Na as a mineralizer will be investigated, aiming to determine solubility with a focus on its temperature dependency. To obtain data for near-identical chemical and physical conditions, a number of molybdenum-capsules with high heat capacity will be employed in each experiment, yielding one gravimetric solubility data point per capsule and experiment. Capsule materials will be made of materials of defined surface conditions that are used as reactor or interior components materials in ammonothermal crystal growth. Obtained solubility data will be analyzed for consistency with trends expected based on theory.

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Art der Arbeit:

Masterarbeit

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Status:

laufend

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