It has been recently shown that microcantilever sensors in dynamic force microscopes possibly exhibit chaotic oscillations due to the nonlinear tip-sample interaction force. In this article, we propose elimination of the chaotic oscillations using the time delayed feedback control method, which has an ability to stabilize unstable periodic orbits embedded in chaotic attractors. An extended operating range of the microscopes is numerically estimated by stability analysis of the target periodic oscillation. We also discuss an improved transient response of oscillation, which allows us to accelerate the scanning rate of the microscopes without reducing their force sensitivity.

Current generations of 4H-SiC metal-oxide-semiconductor field-effect transistors are still challenged by the high number of defects at the SiO 2 /SiC interface that limit both the performance and gate reliability of these devices. One potential source of the high density of interface defect states (D it) is the stepped morphology on commonly used off-axially grown epitaxial surfaces, favoring incomplete oxidation and the formation of defective transition layers. Here we report measurements on intentionally modified 4H-SiC surfaces exhibiting both atomically flat and stepped regions where the generation of interface defects can be directly linked to differences in surface roughness. By combining spatially resolving structural, chemical, optical, and electrical analysis techniques, a strong increase of D it for stepped surfaces was revealed while regions with an atomically flat SiC surface exhibited close-to-ideal interface properties.

Scanning nonlinear dielectric microscopy (SNDM) can be used to visualize polarization distributions in ferroelectric materials and dopant profiles in semiconductor devices. Without using a special sharp tip, we achieved an improved lateral resolution in SNDM through the measurement of super-higher-order nonlinearity up to the fourth order. We observed a multidomain single crystal congruent LiTaO3 (CLT) sample, and a cross section of a metal-oxide-semiconductor (MOS) field-effect-transistor (FET). The imaged domain boundaries of the CLT were narrower in the super-higher-order images than in the conventional image. Compared to the conventional method, the super-higher-order method resolved the more detailed structure of the MOSFET.

We successfully demonstrated the first experimental stabilization of irregular and non-periodic cantilever oscillation in the amplitude modulation atomic force microscopy using the time-delayed feedback control. A perturbation to cantilever excitation force stabilized an unstable periodic orbit associated with nonlinear cantilever dynamics. Instead of the typical piezoelectric excitation, the magnetic excitation was used for directly applying control force to the cantilever. The control force also suppressed the cantilever's occasional bouncing motions that caused artifacts on a surface image.