Authors: Jeong Hyun Moon, Da Il Eom, Sang Yong No, Ho Keun Song, Jeong Hyuk Yim, Hoon Joo Na, Jae Bin Lee, Hyeong Joon Kim
Abstract: 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.
1083
Authors: Sima Dimitrijev, Ji Sheng Han, Jin Zou
Abstract: High-resolution transmission electron microscopy (HR TEM) reveals an atomically flat
SiC surface after oxidation in either NO or dry O2 ambients. This reopens the question of the origin
of the electronically active defects at the SiO2–SiC interface, whose density remains orders of
magnitude higher than in the SiO2–Si interface. Capacitance-transient measurements, analysed in
this paper, demonstrate that the dominant electronically active defects are in the oxide at tunneling
distances from the SiC surface (near-interface traps). The HR TEM results cannot rule out that these
traps are related to carbon/oxygen bonds or even nanometer-sized carbon clusters, which resolves
the apparent inconsistency with the earlier experimental evidence of carbon accumulation at (or
near) the SiO2–SiC interface.
975
Authors: Pawel A. Sobas, Ulrike Grossner, Bengt Gunnar Svensson
Abstract: Using impedance spectroscopy (IS) for the characterization of SiO2/4H-SiC (MOS) structures, insight on the capacitive and resistive contributions in different physical regions of the MOS structures is obtained. Changing the DC bias conditions, semiconductor, interface as well as oxide traps can be detected. The MOS capacitance, as extracted from IS data, is different from the one obtained using capacitance voltage (CV) measurements, due to the possibility of distinguishing different charge transfer processes using IS. For instance, in the investigated capacitors, a clear contribution is revealed from ionic conduction processes at bias voltages close to zero.
501
Authors: Sandeepan DasGupta, Andrew Armstrong, Robert Kaplar, Matthew Marinella, Reinhard Brock, Mark Smith, Stanley Atcitty
Abstract: Carrier generation characteristics in n-type substrate SiC MOS capacitors induced by sub-bandgap energy light are reported. The generation rate is high enough to create an inversion layer in ~20 minutes with monochromatic light (front side illumination) of energy 2.1 eV in 4H-SiC for electric fields smaller than 1 MV/cm. Generation and recovery results strongly indicate involvement of a metastable defect whose efficiency as a generation center increases under hole-rich and decreases under electron-rich conditions. The generation dependence on bias history and light energy shows the defect to have properties consistent with the metastable silicon vacancy / carbon vacancy-antisite complex (VSi / Vc - CSi).
441
Authors: Y. Yang, F. Yu, Ping Han, R.P. Ge, L. Yu
Abstract: Capacitance-voltage method was used to analyze composition of the Si1-xGex alloy films with a stochiometry gradient of Ge, which were epitaxially grown on Si (100) substrate by chemical vapor deposition. Using the capacitance characteristics of Si1-xGex/Si obtained by applying a reserve bias to the Hg electrode probe, the contact barrier height for Hg/Si1-xGexjunction and Si1-xGex/Si junction, and band gap of SSi1-xGex were estimated respectively. With the band gap of Si1-xGex, composition of Si1-xGex in Hg/Si1-xGex junction and Si1-xGex/Si junction were further obtained. Because analyzed Si1-xGex was formed through bilateral inter-diffusion of Si into the epilayer and Ge into the substrate during the deposition, Ge distribution from surface to substrate in Si1-xGex alloy films can be figured out by fitting to diffusion exponential function. The Ge distribution acquired this way was in accordance with the depth profile by auger electron spectrum.
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