GeSi Nanocrystals Photo-Sensors for Optical Detection of Slippery Road Conditions Combining Two Classification Algorithms

Abstract

One of the key elements in assessing traffic safety on the roads is the detection of asphalt conditions. In this paper, we propose an optical sensor based on GeSi nanocrystals embedded in SiO2 matrix that discriminates between different slippery road conditions (wet and icy asphalt and asphalt covered with dirty ice) in respect to dry asphalt. The sensor is fabricated by magnetron sputtering deposition followed by rapid thermal annealing. The photodetector has spectral sensitivity in the 360–1350 nm range and the signal-noise ratio is 102–103. The working principle of sensor setup for detection of road conditions is based on the photoresponse (photocurrent) of the sensor under illumination with the light reflected from the asphalt having different reflection coefficients for dry, wet, icy and dirty ice coatings. For this, the asphalt is illuminated sequentially with 980 and 1064 nm laser diodes. A database of these photocurrents is obtained for the different road conditions. We show that the use of both k-nearest neighbor and artificial neural networks classification algorithms enables a more accurate recognition of the class corresponding to a specific road state than in the case of using only one algorithm. This is achieved by comparing the new output sensor data with previously classified data for each algorithm and then by performing an intersection of the algorithms’ results.

Nanocrystallized Ge-Rich SiGe-HfO2 Highly Photosensitive in Short-Wave Infrared

“…Density functional theory (DFT) computations of the energy gap of alloy GeSi NCs with high Ge content for finding bandgap diameter dependence for different Ge contents and bigger diameters in agreement to the experimental data can be used for the design and characterization of GeSi NCs-based optical sensors [32]. Based on all these results, recently, we developed an optical sensor system with a photoactive layer of GeSi NCs in the SiO 2 matrix that discriminates between different slippery road conditions, to be mounted on a platform for warning drivers in due time and at sufficient distance [33]. The sensor has 360-1350 nm sensitivity and 10 2 -10 3 signal/noise ratio at room temperature.…”

Enhancing Short-Wave Infrared Photosensitivity of SiGe Nanocrystals-Based Films through Embedding Matrix-Induced Passivation, Stress, and Nanocrystallization

“…% Ge and are nonuniformly distributed along the film thickness. 93 They have small size (5 nm) and high density at the bottom part of the structure, and big size (18 nm) and lower density at the top part. This aspect is due to Ge and Si segregation and diffusion influenced by the internal stress along the film depth.…”

Interplay of Quantum Confinement and Strain Effects in Type I to Type II Transition in GeSi Core–Shell Nanocrystals

“…Si/Ge heterostructures have been fabricated using different techniques, such as molecular beam epitaxy, self-assembly, , ion beam and magnetic sputtering deposition, − chemical vapor deposition, , chemical synthesis, and gas-phase and nonthermal plasma synthesis. − They have been integrated into different technological devices, for instance, in high-speed and high-power field-effect transistors, − photodetectors, , linear and nonlinear optics devices, , solar cell systems, , nonvolatile memory, and thermoelectric devices.…”