In initial precursor research for rare-earth (RE) elements the development has mainly been focusing on compounds with high thermal stability like RE β-diketonates and RE cyclopentadienyls which possess limited reactivity complicating their application in thin film fabrication of the high k dielectrics. The enhanced reactivity of the N-coordinated rare earth amidinate precursor class allows milder deposition conditions for RE2O3 thin films by ALD and CVD [1-3, 5] yielding broad ALD windows (150 to 280 °C for Y2O3 ALD) [3].
In the amidinate precursor development, the alkyl groups of the ligand have been systematically varied to optimize the film growth characteristics. Thereby, the symmetric versions were found to provide a higher thermal stability with isopropyl groups being the best compromise between the steric demand and low molecular mass. The size of alkyl group in the backbone should be minimal to avoid carbon embedding in the grown films. The high potential of rare-earth diisopropylformamidinates motivated us to expand our catalogue to the rare-earth element, gadolinium (Strem Catalog #: 64-3575).
Strem Catalog #: 64-3575
Tris(N,N'-di-i-propylformamidinato)gadolinium(III), (99.999+%-Gd) PURATREM Gd-FMD
The versatility of RE amidinates is highlighted by the application in CVD processes for the growth of rare-earth nitride and sulfide thin films [4, 6-8] where GdN is the most investigated one due to its ferromagnetic semiconductor nature. Thus, the oxophility of this material results in high requirements for precursor quality and process design. Gd amidinates in combination with ammonia were found to be the best performing precursor combination and AlN a superior protective layer.[4, 5, 7]
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64-3575: Tris(N,N'-di-i-propylformamidinato)gadolinium(III), (99.999+%-Gd) PURATREM Gd-FMD
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