Performance Optimization of FD-SOI Hall Sensors Via 3D TCAD Simulations.

This work investigates the behavior of fully depleted silicon-on-insulator (FD-SOI) Hall sensors with an emphasis on their physical parameters, namely the aspect ratio, doping concentration, and thicknesses. Via 3D-technology computer aided design (TCAD) simulations with a galvanomagnetic transport model, the performances of the Hall voltage, sensitivity, efficiency, offset voltage, and temperature characteristics are evaluated. The optimal structure of the sensor in the simulation has a sensitivity of 86.5 mV/T and an efficiency of 218.9 V/WT at the bias voltage of 5 V. In addition, the effects of bias, such as the gate voltage and substrate voltage, on performance are also simulated and analyzed. Optimal structure and bias design rules are proposed, as are some adjustable trade-offs that can be chosen by designers to meet their own Hall sensor requirements.

Resistive switching memory characteristics of Ge/GeOx nanowires and evidence of oxygen ion migration.

The resistive switching memory of Ge nanowires (NWs) in an IrOx/Al2O3/Ge NWs/SiO2/p-Si structure is investigated. Ge NWs with an average diameter of approximately 100 nm are grown by the vapor-liquid-solid technique. The core-shell structure of the Ge/GeOx NWs is confirmed by both scanning electron microscopy and high-resolution transmission electron microscopy. Defects in the Ge/GeOx NWs are observed by X-ray photoelectron spectroscopy. Broad photoluminescence spectra from 10 to 300 K are observed because of defects in the Ge/GeOx NWs, which are also useful for nanoscale resistive switching memory. The resistive switching mechanism in an IrOx/GeOx/W structure involves migration of oxygen ions under external bias, which is also confirmed by real-time observation of the surface of the device. The porous IrOx top electrode readily allows the evolved O2 gas to escape from the device. The annealed device has a low operating voltage (<4 V), low RESET current (approximately 22 µA), large resistance ratio (>103), long pulse read endurance of >105 cycles, and good data retention of >104 s. Its performance is better than that of the as-deposited device because the GeOx film in the annealed device contains more oxygen vacancies. Under SET operation, Ge/GeOx nanofilaments (or NWs) form in the GeOx film. The diameter of the conducting nanofilament is approximately 40 nm, which is calculated using a new method.