Evaluation of Homoleptic Guanidinate and Amidinate Complexes of Gadolinium and Dysprosium for MOCVD of Rare-Earth Nitride Thin Films

Abstract

Metal−organic chemical vapor deposition (MOCVD) of thin films of two representative rare-earth nitrides is reported here for the first time. Four homoleptic, all-nitrogen-coordinated, rare-earth (RE) complexes were evaluated as precursors for the respective nitride thin film materials. Two guanidinato complexes [RE{( i PrN)2C(NMe2)}3] [RE = Gd (1), Dy (2)] and two amidinato complexes [RE{( i PrN)2CMe}3] [RE = Gd (3), Dy (4)] were compared and used either as single source precursors or together with ammonia for MOCVD of gadolinium nitride (GdN) and dysprosium nitride (DyN), respectively. The thermal properties of the precursors were studied and the fragmentation patterns were characterized by high-resolution electron impact−mass spectrometry (HR EI-MS). The obtained nitride films were investigated using a series of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), nuclear reaction analysis (NRA), Rutherford backscattering (RBS), and X-ray photoelectron spectroscopy (XPS). The films contain preferentially oriented grains of fcc-GdN and DyN and are contaminated with small amounts of carbon and oxygen (significantly below 10 at. % in the best cases). The temperature-dependent magnetic properties of the films, as measured using a superconducting quantum interference device (SQUID), suggest the existence of small ferromagnetic grains of the rare-earth nitrides that exhibit superparamagnetism. Despite the chemical and structural similarity of the guanidinato and amidinato complexes (1−4), a distinctly different behavior as MOCVD precursors was found for 1 and 2, compared with that for 3 and 4. While the guanidinates operate well as single-source precursors (SSPs), the amidinates are not suited at all as SSPs, but give very good nitride films when used in the presence of ammonia. This characteristic behavior was correlated with the different fragmentation mechanisms, as revealed by EI-MS.

Measurement of gamma-ray production cross sections for nuclear reactions 14N(d,pγ)15N and 28Si(d,pγ)29Si

“…The magnetic field of the magnet is measured by a nuclear magnetic resonance (NMR) fluxmeter [14]. The calibration constant giving the relation between the particle energy and NMR frequency [15] was determined independently using the resonance of the 27 Al(p,γ) 28 Si reaction at 991.86 ± 0.03 keV [16] and the 7 Li(p,n) 7 Be reaction threshold at 1880.44±0.02 keV [17]. Target materials applied for these measurements were a 750 nm thick Al foil, and a 135 µg/cm 2 thick…”

“…Some of the recent applications of this technique concern the production of rare-earth nitride materials (like dysprosium nitride) which are of great interest for a number of applications (e.g. in spintronics) [7]. Rare-earth oxides and rare-earth-scandates are interesting for metal-oxidesemiconductor field-effect transistors (MOSFET) as well as Ge metal-oxide-semiconductor (MOS) transistors [8].…”

Electronic structure of EuN: Growth, spectroscopy, and theory

“…For most the magnetic state is known, 8,9 but much less information is available regarding the electronic structure. Recent progress has been made, especially in the case of GdN, with the demonstration of epitaxial film growth, [10][11][12][13][14] and studies of its electronic and magnetic properties. [15][16][17][18][19][20][21] Far fewer experimental data concerning the rest of the series are available.…”

High temperature oxidation kinetics of dysprosium particles

“…Additionally, dysprosium mononitride (DyN) has been postulated as a suitable surrogate for americium mononitride (AmN) due to its similar physical and chemical attributes in studying its sintering and alloying effects in spent nuclear fuel reprocessing [10][11][12][13][14][15]. DyN has also been investigated as a material for ferromagnetic and semiconductor superlattice structures for spintronic applications [16][17][18].…”