Sensor-based computing minimizes latency and energy consumption by processing data at the capture point, thereby eliminating extensive data transfer and enabling real-time decision-making. Here, we present a breakthrough in in-sensor computing via circularly polarized light detectors that integrate cholesteric liquid crystal reflectors with two-dimensional van der Waals p-n heterostructures. Our device exhibits a high dissymmetry factor (1.90), allowing effective separation of mixed circularly polarized images, along with a rapid photoresponse (4 μs) and wide linear dynamic range (up to 114.1 dB), suitable for analog multiply-and-accumulate operations in convolution-based in-sensor computing. Harnessing these detectors, we propose mixed-multimodal in-sensor computing using the chiral state of circularly polarized light to dynamically control responsivity, which enables the blending of two arbitrary image processing modes within a single, non-reconfigurable circuit. By effectively integrating polarization-sensitive detectors into the in-sensor computing framework, the proposed architecture preserves kernel optimization capabilities while simplifying circuit complexity.

Jongtae Ahn*. Applied Science and Convergence Technology 2024;33:164-6. https://doi.org/10.5757/ASCT.2024.33.6.164

Photodetectors sensitive to the near‐infrared (NIR) range are of great importance for applications in machine vision, autonomous driving, and three‐dimensional (3D) imaging under low‐light or adverse weather conditions. Recently, two‐dimensional (2D) semiconductors have emerged as promising light‐absorbing materials for NIR detection. However, the inevitable majority‐carrier injection from the electrode fundamentally leads to high dark current and poor light‐detection capability, which has constrained the development of 2D semiconductor photodetectors so far. Here, we demonstrate a high‐detectivity NIR photodetector based on a MoTe ₂ /WSe ₂ /Cl–SnSe ₂ unipolar barrier heterostructure. The WSe ₂ layer acts as an efficient majority‐carrier‐blocking barrier, effectively suppressing dark current and achieving a room‐temperature specific detectivity of 6.75 × 10 ⁸ Jones, a linear dynamic range of 62 dB, and an effective −3 dB bandwidth approaching 0.1 MHz under 1310 nm illumination. Using this device as an imager, we show 3D NIR imaging of real objects under low‐illumination conditions, highlighting its potential for applications such as vein visualization and material identification.

NdSbTe is a magnetic topological semimetal in which nontrivial electronic states coexist with antiferromagnetic order, while variation in the Sb/Te composition substantially modifies its electronic and magnetic properties. Here, we investigate the temperature- and magnetic field-dependent electrical transport properties of NdSb_0.5Te_1.5. The electrical resistivity exhibits nonmetallic behavior below approximately 100 K and develops a pronounced high-resistivity state below 4 K, reaching more than three orders of magnitude above its room temperature value. Multiple characteristic anomalies emerge within the high-resistivity state and are systematically suppressed by magnetic fields. The characteristic temperatures and critical fields consistently define multiple transport regimes in the H-T phase diagram. Remarkably, a relatively weak magnetic field of approximately 0.5 T induces an abrupt and hysteretic transition between high and low resistivity states. These results demonstrate an exceptionally large field-tunable resistive response closely coupled to the magnetic state in NdSb_0.5Te_1.5.