Two Intermediates in Ammonothermal InN Crystal Growth: [In(NH3)5Cl]Cl2 and InF2(NH2)

Abstract

AbstractThe ammonothermal synthesis is a promising instrument for synthesis and crystal growth of the metastable semiconductor InN. Two novel intermediates within the ammonothermal InN crystal growth have been synthesized, namely pentaamminechloridoindium dichloride, [In(NH3)5Cl]Cl2, and indium amide difluoride, InF2(NH2). Both intermediates were obtained under ammonothermal conditions (Tmax=663 K, pmax=118.3 MPa, and Tmax=753 K, respectively) in a near‐ammononeutral milieu as established for InN crystal growth, using the respective indium trihalide together with potassium amide as mineralizer system. The crystal structure of [In(NH3)5Cl]Cl2 shows strong structural relations to the corresponding intermediate [Ga(NH3)5Cl]Cl2 within ammonoacidic GaN crystal growth. At ambient pressure, it decomposes above 450 K under release of ammonia. InF2(NH2) shows attributes of a classical MX3 crystal structure, realizing the motif of a hexagonal close packing of (NH)2− together with F− ions and indium occupying one third of the octahedral holes between every layer of the packing. Vibrational spectroscopy for both solid intermediates is reported.