Photoemission investigation of the Schottky barrier at the Sc/3C-SiC (111) interface

Abstract

The Schottky barrier and interfacial chemistry for interfaces formed by evaporation of Sc onto 3C-SiC (111)-(1x1) surfaces at 600 8C has been investigated using in situ X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) and low energy electron diffraction (LEED). Sc was observed to grow in a two-dimensional manner and exhibit a (1x1) LEED pattern up to thicknesses of $2 nm beyond which diffraction patterns were no longer observable. XPS measurements of these same films showed a clear reaction of Sc with the 3C-SiC (111)-(1x1) surface to form a ScSi x and ScC x interfacial layer in addition to the formation of a metallic Sc film. XPS measurements also showed the deposition of Sc induced $0.5 eV of upward band bending resulting in a Schottky barrier of 0.65 AE 0.15 eV. More recently, Sc has garnered significant interest as an electrical contact metal [1], conductive dislocation reducing buffer layer [3,4], and alloying agent with aluminum nitride (AlN) and gallium nitride (GaN) for a variety of piezoelectronic [5][6][7], thermoelectric [8], ferroelectric [9], and optoelectronic applications [10][11][12]. This interest is primarily a result of the high solubility and close lattice matching of Sc with wurtzite structure AlN and GaN (a 0 ¼ 0.3111 and 0.3189 nm), high thermal stability, ductility, and relative ease of deposition [1]. Sc also exhibits reasonably close lattice matching to the (111)/(0001) basal plane of cubic and hexagonal silicon carbide (SiC, a 0 ¼ 0.308 nm). Therefore, Sc could also serve as a potential Ohmic or Schottky contact for high temperature, power, and frequency SiC based electronic devices and as a conductive buffer layer for GaN heteroepitaxy on SiC substrates. For these specific applications, the band alignment of Sc to SiC will play a significant

Carbon-Based Aromatic-Like Nanostructures on the Vicinal SiC Surfaces Induced by Ba Adsorption

“…For the clean SiC surface the spectrum is characterized by the broad band in the binding energy region of 0 ÷ 9 eV below E VBM with major peak at ∼2.2 eV. The similar PES result was obtained for the single-SiC(111) surface 18,31 and for the SiC(100) surface. 13 The surface layer of SiC has some number of the Si surface dangling bonds, Si vacancies and Si dimmer-related states which provide the high chemical and adsorption activity of the surface.…”

“…Recently, the photoemission studies of various SiC polytypes have been reported. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] However, the problems concerning metal/SiC interfaces remain unsolved in many respects to date. There are several studies of adsorption of Cs, 15,16 Na, 17 and Sc 18 metals at the surface of the hexagonal SiC polytype only.…”

Новый тип углеродной наноструктуры на вицинальной поверхности SiС(111)-8-=SUP=-o-=/SUP=-

“…Однако проблемы, связанные с интерфейсами металл/SiC, остаются слабо изученными. Существует несколько работ по адсорбции металлов Cs [6], Na [7] и Sc [8] на поверхности гексагонального политипа SiC. Недавно была изучена электронная структура интерфейса Ba/3C-SiC(111) для случая сингулярной поверхности SiC [9].…”

Synchrotron radiation photoemission study of Ba adsorption on the vicinal SiC(111)-8° surface

“…Alkali-earth metal and alkali metal adsorbates are good candidates for the formation of metal-semiconductor interfaces and Schottky barrier compositions. The relevant electronic properties were studied for Sc/3C-SiC(111) interface (King et al 2015), Rb and Cs adsorption on graphene on SiC(0001) (Watcharinyanon et al 2011) and Na on graphene on SiC(0001) (Watcharinyanon et al 2012). It was found that Rb, Cs and Na deposited on monolayer graphene samples produce an n-type doping with the electron transfer from the metal to the graphene layer.…”