For SiO2/4H–SiC (0001) and (000–1) n-type metal-oxide-semiconductor capacitors, the relationship between flatband voltage and the thickness of oxide was investigated after NO post-oxidation annealing to evaluate the expected flatband voltage (VFB) without a fixed charge effect. After removal of the fixed charge effect, there was an anomalous negative shift of VFB on (0001) 4H–SiC, which would be attributed to the result of dipole layer formation at the interface. The effects of the dipoles were investigated from the perspective of the SiO2/4H–SiC band alignment shift. We could find the correlation between the shift of VFB and that of the band alignment between SiO2 and the 4H–SiC interface; we concluded that stable Si–N bonds at the interface induce a dipole layer, and this is one of the reasons for the unexpected shift reported for VFB or threshold voltage of metal-oxide-semiconductor field-effect transistors, as well as the fixed charge effects. A significant difference in the band alignment on (0001) and (000–1) was also clarified, which would be one of the reasons for the disagreement of VFB on those faces.
A facile method to fabricate a mechanically robust, stretchable solar absorber for stretchable heat generation and an enhanced thermoelectric generator (TEG) is demonstrated. This strategy is very simple: it uses a multilayer film made of titanium and magnesium fluoride optimized by a two-dimensional finite element frequency-domain simulation, followed by the application of mechanical stresses such as bending and stretching to the film. This process produces many microsized sheets with submicron thickness (∼500 nm), showing great adhesion to any substrates such as fabrics and polydimethylsiloxane. It exhibits a quite high light absorption of approximately 85% over a wavelength range of 0.2-4.0 μm. Under 1 sun illumination, the solar absorber on various stretchable substrates increased the substrate temperature to approximately 60 °C, irrespective of various mechanical stresses such as bending, stretching, rubbing, and even washing. The TEG with the absorber on the top surface also showed an enhanced output power of 60%, compared with that without the absorber. With an incident solar radiation flux of 38.3 kW/m, the output power significantly increased to 24 mW/cm because of the increase in the surface temperature to 141 °C.
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