Intermediates during Ammonothermal Synthesis of Crystals of Binary and Higher Metal NitrideSemiconductor Materials

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The main goal of this subproject during the second project period is to deepen the knowledge about the chemical mechanisms in ammonothermal synthesis of binary metal nitride crystals acquired in the first period and to transfer the knowhow to further chemical systems. The spectrum of possible experiments under ammonothermal conditions shall be broadened via (independent) increase of maximal temperature and pressure as well as further development of liner materials.Particularly in the synthesis of GaN under ammonobasic conditions with potassium amide as mineralizer the characterization of the obtained liquid compound might be the key to the understanding of the specific chemical processes at crystal growth conditions. These investigations will be supported by studies of the sodium and potassium amido aluminates, since these compounds according to literature show a quite similar chemistry and present as solids better defined starting materials. As one result we expect further important information for the interpretation of the temperature and pressure dependent solubilities of GaN in sc-NH3 with ammonobasic mineralizers. Related issues are the in situ-studies of dissolved species and processes at the atomic/molecular level during the crystal growth in cooperation with other subprojects (TP 3, 4, 5). The generation of precise property and solubility data is a further important point (cooperation with all TPs).For the production of new materials first possible intermediates in the up to date unknown ammonothermal synthesis of the semiconductors InN and Zn3N2 will be characterized. Based on the obtained information and the advanced experimental possibilities the crystal growth of these interesting materials should be successful. In the following the synthesis of solid solutions of GaN with InN and with transition metal nitrides, e.g. ScN, and rare-earth metal nitrides,, as well as of ternary materials (e.g., ZnSiN2, ZnGeN2 und ZnSnN2 in close cooperation with TP 1) will be carried out. Also in these cases the knowledge of the soluble intermediates is of utmost importance.