Thermal study of an indium trisguanidinate as a possible indium nitride precursor

Abstract

Tris-N,N,-dimethyl-N′,N″-diisopropylguanidinatoindium(III) has been investigated both as a chemical vapor deposition precursor and an atomic layer deposition precursor. Although deposition was satisfactory in both cases, each report showed some anomalies in the thermal stability of this compound, warrenting further investigation, which is reported herein. The compound was found to decompose to produce diisopropylcarbodiimide both by computational modeling and solution phase nuclear magnetic resonance characterization. The decomposition was shown to have an onset at approximately 120 °C and had a constant rate of decomposition from 150 to 180 °C. The ultimate decomposition product was suspected to be bisdimethylamido-N,N,-dimethyl-N′,N″-diisopropylguanidinato-indium(III), which appeared to be an intractable, nonvolatile polymer.

The Endocyclic Carbon Substituent of Guanidinate and Amidinate Precursors Controlling Atomic Layer Deposition of InN Films

“…Thermal decomposition of 1 limited the bubbler temperature. A bubbler temperature of 160 °C for 1 is not optimal as it starts to decompose at 120 °C, but lower temperatures did not afford film deposition due to insufficient vapor pressure. To circumvent the low vapor pressures of 1 and 2 , a fill-empty approach was employed.…”

“…Herein, we explore homoleptic hexacoordinated In­(III) precursors with In–N bonded bidentate ligands for ALD of InN. These molecules, tris­( N , N -dimethyl- N ′, N ″-diisopropylguanidinato)­indium­(III) 1 , tris­( N , N ′-diisopropylamidinato)­indium­(III) 2 , and tris­( N , N ′-diisopropylformamidinato)­indium­(III) 3 (Figure ), have all been recently reported as In precursors for ALD of In 2 O 3 . − We show that the size of the substituent on the endocyclic carbon atom of the ligand backbone has a substantial effect on the film deposition, with the smaller substituents affording films of higher crystalline quality, smoother morphology, lower impurity levels, and optical properties closer to those reported for bulk InN. We suggest that this is explained by improved surface chemistry when the size of the substituent is reduced.…”

The Endocyclic Carbon Substituent of Guanidinate and Amidinate Precursors Controlling ALD of InN Films

“…These molecules -tris(N,N-dimethyl-N',N''-diisoproprylguanidinato)indium(III) (1), tris(N,N'diisopropylamidinato)indium(III) (2) and tris(N,N'-diisopropylformamidinato)indium(III) (3) (Figure 1), have all been recently reported as In precursors for ALD of In2O3. 11,12,13,14,15 We show that the size of the substituent on the endocyclic carbon atom in the ligand backbone has a substantial effect on the film deposition, with the smaller substituents affording films of higher crystalline quality, smoother morphology, lower impurity levels in the deposited InN films and optical properties closer to those reported for bulk InN. We suggest that this is explained by improved surface chemistry when the size of the substituent is reduced.…”

“…Precursor 1 and 2 were purified by recrystallization from hexanes and 3 by sublimation (90 °C at 0.1 mbar). Previously reported thermogravimetric analysis of 1, 2, and 3 showed single step evaporations with onset temperature and residual masses of 175 °C/11.5% 14 , 240 °C/0% 12 and 200 °C/0% 12 , respectively.…”

The Endocyclic Carbon Substituent of Guanidinate and Amidinate Precursors Controlling ALD of InN Films

“…Herein, we explore homoleptic (Figure 1), have all been recently reported as In precursors for ALD of In2O3. 11,12,13,14,15 We show that the size of the substituent on the endocyclic carbon atom in the ligand backbone has a substantial effect on the film deposition, with the smaller substituents affording films of higher crystalline quality, smoother morphology, lower impurity levels in the deposited InN films and optical properties closer to those reported for bulk InN. We suggest that this is explained by improved surface chemistry when the size of the substituent is reduced.…”