The electrical properties of thermally grown and atomic-layer-deposition (ALD) oxides, followed by nitridation treatment, on 4H-SiC substrate were compared. The nitridation treatment was performed with post oxidation annealing in NO atmosphere (NO POA). The best electrical characteristics of the thermally grown and ALD oxides were observed at 120 and 180 min NO POA, respectively. The NO POA treated ALD oxide showed extremely low interface trap density (Dit), less than 1011 eV−1 cm−1. A metal-oxide-semiconductor field-effect-transistor with the ALD oxide showed high field effect mobility, especially in the high electric field region. The reasons for these superior results were also discussed.
The authors attempted to grow a semi-insulating silicon carbide (SiC) epitaxial layer by in situ iron doping. The homoepitaxial growth of the iron-doped 4H-SiC layer was performed by metal-organic chemical vapor deposition using the organo-silicon precursor bis(trimethylsilylmethane) (C7H20Si2) and the metal-organic precursor t-butylferrocene (C14H17Fe). For the measurement of the resistivity of the iron-doped 4H-SiC epilayers, the authors used the on resistance of Schottky barrier diode. Based on the measurement of the on resistance, it is shown that the free carrier concentration was decreased with increasing partial pressure of t-butylferrocene. The resistivity of the iron-doped 4H-SiC epilayer was about 108Ωcm.
The authors attempted to grow a semi-insulating
4H-SiC
epitaxial layer by in situ vanadium doping. The homoepitaxial growth of the vanadium-doped
4H-SiC
layer was performed by metallorganic chemical vapor deposition using the organosilicon precursor bis-trimethylsilylmethane (BTMSM,
normalC7normalH20Si2
) and the metallorganic precursor bis-cyclopentadienylvanadium (Verrocene,
normalC10normalH10V
). The vanadium doping effect on the crystallinity of the epi layer was very destructive. Vanadium-doped epi layers grown under normal conditions had various crystal defects such as micropipes and polytype inclusions, but this crystallinity degradation was overcome by elevating the growth temperature. For measurement of the resistivity of the highly resistive vanadium-doped
4H-SiC
epi layers, the authors used the on-resistance technique. Based on the measurements of the on-resistance of the Schottky barrier diode fabricated using the vanadium-doped epi layers, it was revealed that the residual donor concentration of the epi layers was decreased with increasing partial pressure of verrocene. The resistivity of the in situ vanadium-doped
4H-SiC
epi layer was about
107–1012Ωcm
.
The La2O3 and Al2O3/La2O3 layers were grown on 4H-SiC by atomic layer deposition (ALD) method. The electrical properties of La2O3 on 4H-SiC were examined using metal-insulator-semiconductor (MIS) structures of Pt/La2O3(18nm)/4H-SiC and Pt/Al2O3(10nm)/La2O3(5nm)/4H-SiC. For the Pt/La2O3(18nm)/4H-SiC structure, even though the leakage current density was slightly reduced after the rapid thermal annealing at 500 oC, accumulation capacitance was gradually increased with increasing bias voltage due to a high leakage current. On the other hand, since the leakage current in the accumulation regime was decreased for the Pt/Al2O3/La2O3/4H-SiC MIS structure owing to the capped Al2O3 layer, the capacitance was saturated. But the saturation capacitance was strongly dependent on frequency, indicating a leaky interfacial layer formed between the La2O3 and SiC during the fabrication process of Pt/Al2O3(10nm)/ La2O3(5nm)/ 4H-SiC structure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.