Microscopic study of electrical properties of CrSi 2 nanocrystals in silicon
- PDF / 662,656 Bytes
- 5 Pages / 595.276 x 793.701 pts Page_size
- 85 Downloads / 136 Views
NANO REVIEW
Open Access
Microscopic study of electrical properties of CrSi2 nanocrystals in silicon László Dózsa1*, Štefan Lányi2, Vito Raineri3, Filippo Giannazzo3, Nikolay Gennadevich Galkin4 Abstract Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy of Cr onto n-type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements. Atomic force microscopy (AFM), conductive AFM and scanning probe capacitance microscopy (SCM) were applied to reveal morphology and local electrical properties. The scanning probe methods yielded specific information, and tapping-mode AFM has shown up to 13-nm-high large-area protrusions not seen in the contact-mode AFM. The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface. SCM has revealed NCs deep below the surface not seen by AFM. The electrically active probe yielded significantly better spatial resolution than AFM. The conductive AFM measurements have shown that the Cr-related point defects near the surface are responsible for the leakage of the macroscopic Schottky junctions, and also that NCs near the surface are sensitive to the mechanical and electrical stress induced by the scanning probe. Introduction Chromium disilicide (CrSi2) is a narrow band semiconductor (E g = 0.35 eV [1]), which can be epitaxially grown on Si (111) [2]. Strong increase of hole mobility and decrease of hole concentration have been observed in CrSi2 epitaxial films on Si(111) [3] that corresponds to considerable alterations in their band structure. In previous studies of Cr deposition on Si(111) the formation of self-organized semiconductor CrSi2 islands has been observed by differential optical spectroscopy (DOS) and the threshold for 3D nanosize island formation has been determined [4]. The MBE growth of silicon cap over the CrSi2 islands was found to be optimal at 700°C, with 50-nm Si cap thickness [4]. Under these conditions silicon-silicide heterostructures with CrSi2 nanocrystallites (NCs) have been grown from 0.6-nm Cr deposited onto 550°C silicon [4]. The electrical characteristics were measured in 400 μm × 400 μm Schottky junctions. Optical properties of the samples were studied in an ultrahigh vacuum (UHV) chamber “VARIAN” with a base pressure of 2 × 10 -8 Pa equipped with AES and * Correspondence: [email protected] 1 Research Institute for Technical Physics and Materials Science, P. O. Box 49, H-1525 Budapest, Hungary Full list of author information is available at the end of the article
DOS [5] facilities. A new migration mechanism of the CrSi2 NCs was found, the NCs are transferred through nanopipes [6], which results in CrSi2 NCs with different depth distributions. Macroscopic Schottky junctions include large number of NCs in differen
Data Loading...
