Nonmonotonic wavelength dependence of the polarization-sensitive infrared photoresponse of an anisotropic semimetal

Abstract

Layered semimetals with in-plane anisotropy are promising for advanced polarization-sensitive infrared detection. It is required to investigate the polarization-dependent photoresponse of semimetals over the whole visible-to-long-wave-infrared range and reveal the...

Symmetry-Reduction Enhanced Polarization-Sensitive Photoresponse Based on One-Dimensional van der Waals Materials

“…According to the crystal structure and its HAADF in Figure 1, the b-axis of Nb 2 Pd 1−x Se 5 is defined as the 90°p olarization angle, and the 0°polarization angle is perpendicular to the b-axis. The critical figure-of-merit for polarization sensitivity is the degree of linear polarization (DOLP), 36,48 S1 in the Supporting Information, which further demonstrates its promising prospects for polarization-sensitive photodetection. To further confirm its versatility, other 1D vdW Nb 2 Pd 1−x Se 5 devices have been fabricated, which also exhibit excellent polarization-sensitive photoresponses, as shown in Figure S12 in the Supporting Information.…”

“…This nonmonotonic wavelength-dependent anisotropy could be attributed to the polarization-selective excitation of interband transition associated with asymmetrically distributed electron orbitals. 48 This prominent wavelength selectivity of the Nb 2 Pd 1−x Se 5 device makes it a promising candidate in polarization-sensitive photodetection toward a specific wavelength.…”

“…According to the crystal structure and its HAADF in Figure , the b -axis of Nb 2 Pd 1– x Se 5 is defined as the 90° polarization angle, and the 0° polarization angle is perpendicular to the b -axis. The critical figure-of-merit for polarization sensitivity is the degree of linear polarization (DOLP), , which can be calculated by σ = ( I max – I min )/( I max + I min ), where the I max and I min denote the maximum and minimum photocurrent. The maximum DOLP of the Nb 2 Pd 1– x Se 5 devices is calculated to be around 0.85, which is probably due to the unique 1D nanostructure and symmetry reduction induced by partial occupation of the Pd sites.…”

“…The DOLP increases from 0.63 to 0.85 when the excitation laser wavelength increases from 520 to 638 nm and then decreases to 0.59 when the excitation laser wavelength further increases to 850 nm. This nonmonotonic wavelength-dependent anisotropy could be attributed to the polarization-selective excitation of interband transition associated with asymmetrically distributed electron orbitals . This prominent wavelength selectivity of the Nb 2 Pd 1– x Se 5 device makes it a promising candidate in polarization-sensitive photodetection toward a specific wavelength.…”

Bias-dependent photoresponse of Td-WTe2 grown by chemical vapor deposition

“…Moreover, the gapless linear * Authors to whom any correspondence should be addressed. dispersed band structure of T d -WTe 2 enables the detection of energy photon extendable to long-wavelength infrared or even Terahertz regime [16]. Recent experimental and theoretical study reports that the WTe 2 anisotropic negative photocurrent comes from the angle-bandgap opening under polarized light irradiation [17].…”