In Situ Activation of an Indium(III) Triazenide Precursor for Epitaxial Growth of Indium Nitride by Atomic Layer Deposition

Abstract

Indium nitride (InN) is characterized by its high electron mobility, making it a ground-breaking material for high frequency electronics. The difficulty of depositing high-quality crystalline InN currently impedes its broad implementation in electronic devices. Herein, we report a new highly volatile In(III) triazenide precursor and demonstrate its ability to deposit high-quality epitaxial hexagonal InN by atomic layer deposition (ALD). The new In(III) precursor, the first example of a homoleptic triazenide used in a vapor deposition process, was easily synthesized and purified by sublimation. Thermogravimetric analysis showed single step volatilization with an onset temperature of 145 °C and negligible residual mass. Strikingly, two temperature intervals with selflimiting growth were observed when depositing InN films. In the high-temperature interval, the precursor underwent a gas-phase thermal decomposition inside the ALD reaction chamber to produce a more reactive In(III) compound while retaining self-limiting growth behavior. Density functional theory calculations revealed a unique two-step decomposition process, which liberates three molecules of each propene and N 2 to give a smaller tricoordinated In(III) species. Stoichiometric InN films with very low levels of impurities were grown epitaxially on 4H-SiC. The InN films deposited at 325 °C had a sheet resistivity of 920 Ω/sq. This new triazenide precursor enables ALD of InN for semiconductor applications and provides a new family of M−N bonded precursors for future deposition processes.

Fabrication of Semi-Transparent SrTaO2N Photoanodes with a GaN Underlayer Grown via Atomic Layer Deposition

“…38 The detailed synthetic procedure of the Ga(III) triazenide precursor is provided in our previous reports. 38,42 Prior to the deposition, the 4H−SiC substrates were cleaned in solutions of [1:1:5 solution of H2O2 (30%), NH3 (25%), and H2O] and [1:1:5 solution of H2O2 (30%), HCl (37%), and H2O] to remove potential organic and inorganic contaminants. A hot-wall Picosun R-200 equipped with a Litmas remote plasma source was used for the deposition.…”

Synthesis and Thermal Study of Hexacoordinated Aluminum(III) Triazenides for Use in Atomic Layer Deposition

“…In previous work, we demonstrated high quality thin films of indium nitride and gallium nitride by ALD, using the Ga(triaz)3 and In(triaz)3 as precursors, respectively. 32,31 From the thermal properties of the compounds, we speculated that the depositions are activated by gas-phase decomposition of the precursor in the ALD reactor.…”

“…Homoleptic hexacoordinated Al(III) triazenide complexes have previously been reported 29,30 , however, they are not volatile due to their 1,3-diphenyltriazenide ligands. Recently, we reported the first examples of highly volatile homoleptic 1,3-dialkyltriazenide complexes, tris(1,3-diisopropyltriazenide)In(III) (In(triaz)3) 31 and Ga(III) (Ga(triaz)3) 32 , and their use as ALD precursors. These new triazenide precursors underwent gas-phase decomposition at higher temperatures inside the ALD reactor, giving a smaller and more reactive M(III) species.…”

Synthesis, Characterization, and Thermal Study of Divalent Germanium, Tin, and Lead Triazenides as Potential Vapor Deposition Precursors

“…Recently, we explored the 1,3-dialkyltriazenide ligand for group 13 metals and used the In(III) and Ga(III) 1,3-diisopropyltriazenide precursors for ALD of InN and GaN. 33 − 35 To further explore the 1,3-dialkyltriazenide ligand, we envisaged its ability to stabilize divalent group 14 elements. This would potentially give a new class of tetracoordinated M–N bonded group 14 precursors for ALD.…”