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This paper describes the growth and characterisation of Si/SiC heterojunction structures. Heterojunction structures are of interest for low on-resistance diodes and as potential solutions to fabricating SiC MOS devices with lower interface state densities. The formation of the Si/SiC heterojunction using Chemical Vapour Deposition (CVD), Molecular Beam Epitaxy (MBE), Electron Beam Evaporation under UHV conditions (EBE-UHV) and Layer Transfer (LT) are reported. The physical nature of Si/SiC structures has been investigated using scanning electron microscopy (SEM). Results of electrical characterisation of the Si/SiC heterojunctions, are also reported. Finally, thermal oxidation of a Si / SiC heterojunction structures has been performed. The C(V) characteristics of the resulting oxides are compared to conventional thermal oxides on SiC.

This paper reports the investigation of epitaxial graphene growth on 4H-SiC substrates. Growth has been performed under ultra high vacuum (UHV) conditions at temperatures ranging from 1150 to 1250°C, and the formation of the graphene layer has been monitored using X-ray photoelectron spectroscopy (XPS). A gradient of 100°C in temperature was introduced across the sample in order to grow a wide range of thicknesses along the sample. Atomic force microscopy (AFM) of the surface shows that the epitaxial graphene layer follows the topography of the bulk material and introduces very little surface roughness. This paper also reports the electrical characterisation of the graphene layers.

This paper describes the fabrication of Ni and Ti contacts to single crystal, boron-doped diamond. The electrical performance of metal-diamond contacts has been investigated using current-voltage I(V) characterization of circular transmission line model (CTLM) test structures. X-ray photoelectron spectroscopy (XPS) analysis of Ti/diamond contacts has been performed and is correlated with CTLM results. Post deposition annealing of metal-diamond contacts has a dramatic influence on contact resistivity, with lower resistances observed after annealing at 900ºC. Specific contact resistances as low as 9 x 10-5 Ω.cm2 have been obtained. The effect of doping (via epitaxial growth and boron implantation) on metal-diamond contacts is also reported.

The high density of interface states of thermally grown oxides on silicon carbide has prompted research into alternative oxidation methods and post oxidation anneals. One such alternative is oxidation of a deposited sacrificial silicon layer. A recent variation of this technique is a partial oxidation of the deposited Si layer, so that a thin Si layer remains between the SiO2 and SiC layers. If the SiO2/Si interface has lower interface state densities than the SiO2/SiC interface, the SiO2/Si/SiC hetero-structure could yield improved channel mobilities in MOS devices. Moreover, by correct optimization of the MOSFET device structure, breakdown can be designed to occur in the bulk SiC layer, thus maintaining a high blocking voltage. Post oxidation annealing in N2O is another technique often used to reduce interface state densities. However, little is known about the chemical and physical nature of these N2O oxidized dielectrics. Ellipsometric and Medium Energy Ion Scattering (MEIS) investigations of conventional SiO2/SiC interfaces compared with SiO2/Si/SiC hetero-junction structures and N2O oxidized samples are reported.

The investigation of the silicon carbide surface after a sacrificial silicon oxidation technique is reported. Oxidation of SiC is a necessary step in the fabrication of MOS devices and device termination features such as field plates. Device processing requires the etching of windows through the oxide layer to form features such as metal / SiC contacts. However, this work indicates that a thin interfacial Si-O-C layer is still present after etching the oxide with hydrofluric acid (HF). Ellipsometry and X-ray photoelectron spectroscopy (XPS) have been used to evaluate this interfacial layer formed after oxide growth and after subsequent removal of oxide layers. An XPS analysis of the surface after removal of the oxide revealed that silicon, oxygen and carbon were all present in the remaining layer, which could not be removed by annealing at temperatures up to 1000°C. The Si-O-C layer could be eliminated by altering the oxidation conditions or by using a sacrificial silicon layer oxidation process. Ni Schottky barrier diodes fabricated on the 4H-SiC surface after removal of the oxide, displayed slightly higher ideality factors than those of diodes fabricated on untreated 4H-SiC samples.

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