ERBIUM ALKYLAMIDINATES

Erbium tris (1,3-bis(tert-butyl)acetamidinate) Er(tBuNCMeNtBu)3

Fig. . Er[MeC(NBut)2]3 ALD deposition of Er2O3 films.

     Erbium tris(bis(tert-butyl)acetamidinate) Er(tBuNCMeNtBu)3 (as well as series of other lanthanide acetamidinates  Ln(tBuNC(CH3)NtBu)3 (Ln = Y, La, Ce, Nd, Eu, Lu) ) was synthesized by the treatment of anhydrous ErCl3 (or other corresponding LnCl3) in THF at RT with 3 equivalents of Li(1,3-di-tert-butylacetamidinate) (prepared in situ from the di-tert-butylcarbodiimide and methyllithium), in 57–72% yield. The molecular structure of the synthesized  Er(tBuNCMeNtBu)3 (and other Ln amidinates) is monomeric with distorted octahedral geometry about the lanthanide(III) ions,  as determined by the single crystal XRD.. Er(tBuNCMeNtBu)3 as well as other new complexes, is thermally stable at >300 °C, and sublimes without decomposition at ca.180–220 °C/0.05 Torr. [[i]]

 [i] J. Päiväsaari, Ch.L. Dezelah, IV, D. Back, H.M. El-Kaderi, M.J. Heeg, M. Putkonen, L. Niinistö, Ch.H. Winter, J. Mater. Chem., 2005, 15, 4224-4233, DOI: 10.1039/B507351K, « Synthesis, structure and properties of volatile lanthanide complexes containing amidinate ligands: application for Er2O3 thin film growth by atomic layer deposition »

Er(tBuNC(CH3)NtBu)3 for Er2O3 by ALD

Fig . Growth rate of Er2O3 films deposited from Er[MeC(NBut)2]3

     Er(tBuNC(CH3)NtBu)3 with O3 as oxidiser was applied for the atomic layer deposition of Er2O3 films. The growth rate increased linearly from 0.37 Å/cycle to 0.55 Å/cycle when increasing growth temperature from 225°C to 300°C. At substrate temperatures >300°C large thickness gradients across the substrates were observed, suggesting thermal decomposition of the precursor (start of MOCVD-like growth). The increase of pulse length of Er(tBuNC(CH3)NtBu)3 precursor from 1.0 and 3.0 s, slightly increased film growth rate from 0.39 to 0.51 Å/cycle. Growth rate varied linearly with the number of deposition cycles at 250°C. Slightly oxygen-rich Er2O3 films were grown at substrate temperatures 250-300 °C with low level of contaminations: C (1.0–1.9%), H (1.7–1.9%) and F (0.3–1.3 atom%), as demonstrated by time of flight elastic recoil analyses. Carbon and slight excess of oxygen in the grown Er2O3 layers is due to the presence of carbonate species, as was determined by the IR spectroscopy. Below 300 °C the as-deposited films were X-Ray amorphous, but at 300 °C reflections due to cubic Er2O3 became visible. AFM rms surface roughness of 0.3 and 2.8 nm was found in the films grown at 250 and 300 °C. [[i]]

 [i] J. Päiväsaari, Ch.L. Dezelah, IV, D. Back, H.M. El-Kaderi, M.J. Heeg, M. Putkonen, L. Niinistö, Ch.H. Winter, J. Mater. Chem., 2005, 15, 4224-4233, DOI: 10.1039/B507351K, « Synthesis, structure and properties of volatile lanthanide complexes containing amidinate ligands: application for Er2O3 thin film growth by atomic layer deposition »

Er(tBuNC(Me)NtBu)3 for Er-doped Si nanocrystals by CVD

    Erbium tris (bis(tert-butyl)acetamidinate) Er(tBuNCMeNtBu)3 (and for comparison  erbium diketonate Er(thd)3) was tested as precursor for the growth of erbium-doped Si nanocrystals using a CVD process with Si2H6 as the silicon source.The Si:Er nanocrystals were prepared at 1000 °C  by the co-pyrolysis of Er(tBuNC(Me)NtBu)3 and disilane in a dilute He stream. The grown layer structure, composition, and photophysical properties were studied by  HREM, selected area electron diffraction, EDX, PL and extended x-ray absorption spectroscopy. Er-doped Si nanocrystals doped using Er(tBuNCMeNtBu)3 are larger in size , have narrower size distribution and have larger average Er concentration in the nanocrystal , as compared to the doping using erbium β-diketonate precursors in the identical conditions. Characteristic 1540 nm emission was detected in the Si:Er nanocrystals emitted by a silicon exciton-mediated pathway, as was determined by the steady state PL measurements with varying excitation wavelength. Thus, it was demonstrated that the optimal choice of precursor dopant chemistry (Er(tBuNCMeNtBu)3  vs Er(thd)3) has  significant effect on resultant nanoparticle properties.[[i]]

[i] J.Ji, R.A. Senter, L.R Tessler, D. Back, Ch.H Winter, J.L. Coffer, Nanotechnology 2004, 15 643 doi:10.1088/0957-4484/15/5/041, « Rare earth doped silicon nanocrystals derived from an erbium amidinate precursor »

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