Effects of annealing on arrays of Ge nanocolumns formed by glancing angle deposition

• Published in: Applied surface science Vol. 258; no. 24; pp. 9762 - 9769
• Main Authors: Khare, C., Gerlach, J.W., Höche, T., Fuhrmann, B., Leipner, H.S., Rauschenbach, B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2012; Elsevier
• Subjects: Annealing; Arrays; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition; Exact sciences and technology; Ge nanocolumns; Germanium; Glancing angle deposition; Merging; Morphology; Nanostructure; Physics; Re-crystallization; Recrystallization; Silicon substrates; Thermal annealing; Ge nanocolumns; Thermal annealing; Re-crystallization; Glancing angle deposition; Recrystallization; Germanium; Arrays
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2012.06.027

► Free-standing, polycrystalline Ge nanocolumn arrays are obtained by controlled thermal annealing. ► Annealing induces considerable morphology coarsening and re-crystallization at ∼500°C. ► Nanostructures deposited on pre-patterned substrates retained their shape even at ∼700°C. ► TEM investigation revealed nano-crystalline domains of the order of 5-30nm within annealed nanostructures. Post-deposition thermal annealing of glancing angle deposited Ge nanocolumn arrays was carried out in a continuous Ar-flow at temperatures ranging from TA=300 to 800°C for different annealing durations. Morphological alterations and the recrystallization process induced by the thermal annealing treatment were investigated for the Ge nanocolumns deposited on planar and pre-patterned Si substrates. From X-ray diffraction (XRD) measurements, the films annealed at TA≥500°C were found to be polycrystalline. On planar Si substrates, at TA=600°C nanocolumns exhibited strong coarsening and merging, while a complete disintegration of the nanocolumns was detected at TA=700°C. The morphology of nanostructures deposited on pre-patterned substrates differs substantially, where the merging or column-disintegration effect was absent at elevated annealing temperatures. The two-arm-chevron nanostructures grown on pre-patterned substrates retained their complex shape and morphology, after extended annealing intervals. Investigations by transmission electron microscopy revealed nanocrystalline domains of the order of 5–30nm (in diameter) present within the chevron structures after the annealing treatment.