Subproject 2



Intermediates in the ammonothermal synthesis of single crystals of binary and higher metal nitride semiconductor materials


The primary objective of this sub-project is to shed light on the chemistry of formation of single crystals of binary (also quasi-binary and solution phases) metal nitride semiconductor materials in supercritical ammonia with respect to temperature and pressure as well as on raw materials, concentrations and other dissolved substances. Therefore, it is necessary to characterize all the intermediates involved comprehensively, in order to acquire a better understanding of the species involved in the solution and deposition processes of the crystal growth and of the assembly of impurities (transition metal compounds/defects) as well. With the growth process of GaN as an example, these steps shall be investigated intensively. Based on the extensive characterization of the intermediates, the generic knowledge regarding the relevant compounds shall be extended considerably and potential precursors for GaN based materials shall be developed. At the same time we want to synthesize novel ammoniates, amides, imides and nitrides. In the next step, the research will be extended to the synthesis of further semiconductor materials (AlN, InN, Zn3N2).

The strategic aim is the reimplementation of ammonothermal synthesis, which was formerly developed by leading German scientists but nowadays is scarcely used anymore in the German synthesis chemistry. Moreover, we want to conserve and develop the available knowledge.