n-type silicon wafers were doped by boron using a spin-on doping method. A XeCl pulsed excimer laser (λ = 308 nm) was used to irradiate the sample at room temperature. Properties such as sheet resistance, carrier concentration profile, Hall mobility and structural defects were then determined. The results show that the sheet resistance decreases with an increase of laser fluence as well as with an increase in pulse number. It attains a low value of 10 2 −1 for laser fluence above 1.0 J cm −2 . An optimal doping profile with surface carrier concentration of 10 18 cm −3 and a junction depth of 0.36 µm was achieved by 25 pulses of 1.5 J cm −2 irradiation. Channelled Rutherford backscattering spectroscopy showed that no obvious lattice damage exists in the doped Si wafer.

In this paper, a novel 3/27/24 (pole pairs of inner rotor permanent magnet [PM]s/modulator/outer rotor PMs) high torque density yokeless magnetic gear with asymmetric Halbach PM array is presented and optimized for electric vehicle powertrain. The key is to improve the torque performance by replacing the magnetic steel with the light nonmagnetic material as the rotor core and employing the embedded magnetic steel bar as well as trapezoidal PM structure to form a low magnetic resistance in the magnetic circuit. The proposed machine has significant performance improvements in two aspects. Firstly, it has high torque density and low iron loss with the yokeless structure. Secondly, it has a high anti-saturation capability and low torque ripple with the asymmetric Halbach PM array and the embedded magnetic steel bar. The proposed structure is optimized by the co-simulation of the finite-element method and C++ optimization software. For a clear evaluation, the proposed structure is compared with generalized solutions in terms of performance and cost. Comparison results indicate that the proposed solution has the highest output torque, torque density, and torque per PM weight among solutions, reaching 214.1 N⋅m, 58.2 N⋅m/kg, and 95.6 N⋅m/kg, which greatly enhances the performance of the magnetic gear.