SiNW Design by Induced Current to Achieve Excellent Absorption for Linearly Polarized Photodetector

Silicon nanowires (SiNWs) with good extinction performance achieve light capture larger than own cross-section. However, the isotropic response of the polarization angle and the narrow response spectrum of SiNWs limit their application in optoelectronic detectors. In this work, we designed a kind of oblate SiNWs with excellent anisotropic response and wide absorption spectrum, which is suitable for linear polarized light detection. According to the propagation characteristics of electromagnetic waves in the Si material medium, it is found that the induced current presents a vortex flow in the polarization plane of the incident light. Meanwhile, extending the scale of SiNWs in the polarization plane increases the number and mode of induced current to accelerate the attenuation of light in SiNWs for broadens the response spectrum. In addition, this scale extending changes the axial symmetry of SiNWs to achieve anisotropic response. Based on numerical simulation technology, it is obtained that when the incident light wavelength is 420 nm, the light absorption coefficient (Qabs) of oblate SiNWs is 11.42 higher than that of cylindrical SiNWs. The excellent Qabs anisotropy ratio (Qmax/Qmin) of oblate SiNWs can be achieved in the range of 400 nm to 650 nm, of which the maximum value is 74.18. This provides ideas for the design of semiconductor nanowires and their application in photodetectors.