Growth behavior and microstructure of Co–Ge films prepared on GaAs substrate by high-temperature sequential deposition

Growth evolution and characterization of ultra-thin CoGe2 films synthesized via a catalytic solid–vapour reaction technique

“…In the solid-state reaction of Co with Ge, the phase formation sequence was found to proceed through intermediate CoGe and Co 5 Ge 7 phase evolution before ending in CoGe 2 phase structures. 2,3,13,14,18,46 From a thermodynamics point of view, it is wellknown that, for the reaction involving deposited metals and chemical elemental substrates (Ge or Si), the rst formed phase would be the one with the highest metal content having the lowest heat of formation. 47 This would be the case for the cobalt germanide thin lms synthesized via solid state annealing routes, which follows possibly the bulk diffusion properties.…”

“…Thin lms of metal germanides are of considerable interest to be integrated into very large scale integration (VLSI) circuits as interconnects or ohmic contacts not only for Si and Ge based electronic devices but also for other alternative compound semiconductors. [1][2][3][4][5][6][7][8][9][10][11][12] This is primarily due to their low resistivity, good thermal stability and resistance to oxidation. Among the transition metal germanides, CoGe 2 has been well studied by many researchers for Ge based technology and scarcely for other semiconductor substrates.…”

“…2,6,[13][14][15] The synthesis of CoGe 2 lms by thermally induced solid state reaction of PVD sequentially deposited Co and Ge lms on Si and GaAs substrates requires high temperatures (600 C) 18,19 and results in the chemical interaction of Co-Ge with Ga/As during annealing. 3,20 It should be emphasized here that the aforementioned studies on CoGe 2 lms deal with higher thicknesses ($100 nm) and are relevant only for higher technology nodes.…”

Morphological evolution of epitaxial cobalt–semiconductor compound layers during growth in a scanning tunneling microscope

“…13,14 However, with the exception of a new metastable cubic CoSi 2 phase with a CsCl structure that was found by von Känel et al in epitaxially grown layers, 15 only ␣-Co 2 Si, cubic CoSi, and cubic CoSi 2 (CaF 2 ) have ever been detected in thin films. 6,8,18 A. Reactive deposition epitaxy of CoÕSi"001… and CoÕGeÕSi"001… Slow metal deposition onto a substrate at high temperature ensures a low effective metal concentration at the growth interface, i.e., every metal atom arriving at the sur-face reacts immediately, and hence there is no metal accumulation. 13,14 However in thin films the only phases to have ever been observed to form were CoGe, Co 5 Ge 7 , and CoGe 2 .…”

“…Yet, it does not grow as a monocrystalline two-dimensional layer on the Si͑001͒ surface, rather it forms misoriented threedimensional islands. 7,8 In this work we try to shed light on the factors that affect surface morphology of ultrathin heteroepitaxial cobaltsemiconductor compound layers in relation to the kinetics of phase formation in those layers. 6 CoGe 2 forms threedimensional islands on Ge/Si͑001͒ that are very similar to the CoSi 2 ones on Si͑001͒.…”