Electrical data obtained from deep level transient spectroscopy investigations on deep defect centers in the 3C, 4H, and 6H SiC polytypes are reviewed. Emphasis is put on intrinsic defect centers observed in as‐grown material and subsequent to ion implantation or electron irradiation as well as on defect centers caused by doping with or implantation of transition metals (vanadium, titanium, chromium, and scandium).
Graphene is an outstanding electronic material, predicted to have a role in post-silicon electronics. However, owing to the absence of an electronic bandgap, graphene switching devices with high on/off ratio are still lacking. Here in the search for a comprehensive concept for wafer-scale graphene electronics, we present a monolithic transistor that uses the entire material system epitaxial graphene on silicon carbide (0001). This system consists of the graphene layer with its vanishing energy gap, the underlying semiconductor and their common interface. The graphene/semiconductor interfaces are tailor-made for ohmic as well as for schottky contacts side-by-side on the same chip. We demonstrate normally on and normally off operation of a single transistor with on/off ratios exceeding 10 4 and no damping at megahertz frequencies. In its simplest realization, the fabrication process requires only one lithography step to build transistors, diodes, resistors and eventually integrated circuits without the need of metallic interconnects.
In this article, the electrical properties of 3C-SiC are described and its potential for metal-oxide semiconductor field-effect transistors (MOSFETs) is demonstrated. The density of traps, D IT , at the interface of 3C-SiC/SiO 2 capacitors is determined by the conductance method subsequent to various processing steps; the origin of the interface traps is discussed. Lateral and vertical 3C-SiC MOSFET devices of varying cell and device size are designed with hexagonal and squared cell geometry, and are fabricated side by side with MOS Hall bar structures. The electrical parameters of the MOSFETs are determined, and the free electron areal density and Hall mobility are measured in the channel of the MOS Hall bar structures. Based on the charge-sheet model, D IT is also obtained from the Hall investigations.
Hall-effect and infrared-absorption measurements are performed on n-type 4H-SiC samples to investigate the energy positions of the ground state and the excited states of the nitrogen donor in the 4H polytype of silicon carbide. Two electrically active levels (Hall effect) and three series of absorption lines (infrared spectra) are assigned to two nitrogen donor species which substitute on the two inequivalent lattice sites (h,k) in 4H-SiC. Valley-orbit splitting of the ground-state level of the nitrogen donors on hexagonal sites (h) is found to be equal to ΔEvo(h)=7.6 meV. It is shown that the energy position of excited states of both nitrogen donors can be calculated by the effective-mass approximation by assuming anisotropic effective masses m⊥=0.18m0 and m∥=0.22m0. The influence of the two inequivalent lattice sites on the values of ionization energy and valley orbit splitting of the nitrogen donor ground-state levels is discussed.
An electrically active defect has been observed at a level position of ϳ0.70 eV below the conduction band edge (E c ) with an extrapolated capture cross section of ϳ5ϫ10 Ϫ14 cm 2 in epitaxial layers of 4H-SiC grown by vapor phase epitaxy with a concentration of approximately 1ϫ10 13 cm Ϫ3 . Secondary ion mass spectrometry revealed no evidence of the transition metals Ti, V, and Cr. Furthermore, after electron irradiation with 2 MeV electrons, the 0.70 eV level is not observed to increase in concentration although three new levels are observed at approximately 0.32, 0.62, and 0.68 eV below E c with extrapolated capture cross sections of 4ϫ10 Ϫ14 , 4ϫ10 Ϫ14 , and 5ϫ10 Ϫ15 cm 2 , respectively. However, the defects causing these levels are unstable and decay after a period of time at room temperature, resulting in the formation of the 0.70 eV level. Our results suggest strongly that the 0.70 eV level originates from a defect of intrinsic nature. The unstable behavior of the electron irradiation-induced defects at room temperature has not been observed in the 6H-SiC polytype.
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