A Back-Illuminated Time-of-Flight Image Sensor with SOI-Based Fully Depleted Detector Technology for LiDAR Application

Abstract

A back-illuminated time-of-flight (ToF) image sensor based on a 0.2 µm silicon-oninsulator (SOI) CMOS detector technology using fully-depleted substrate is developed for the light detection and ranging (LiDAR) applications. A fully-depleted 200 µm-thick bulk silicon is used for the higher quantum efficiency (QE) in a near-infrared (NIR) region. The developed SOI pixel structure has a 4-tapped charge modulator with a draining function to achieve a higher range resolution and to cancel background light signal. A distance is measured up to 27 m with a range resolution of 12 cm at the outdoor and average light power density is 150 mW/m 2 @30 m.

A Time-of-Flight Range Sensor Using Four-Tap Lock-In Pixels with High near Infrared Sensitivity for LiDAR Applications

“…A prototype TOF range sensor with the proposed four-tap lock-in pixel is implemented using a 0.2 µ m SOI detector technology [17]. The die micrograph and block diagram of the implemented chip are shown in Figure 8.…”

“…To address the issues for next-generation applications of TOF imagers, this paper proposes a backside illuminated (BSI) silicon-on-insulator (SOI) based four-tap lock-in pixel indirect TOF imager using short-pulse modulation [17]. The proposed indirect TOF pixel has multi-tapped gates for signal outputs and a high-speed charge draining gate and uses short light pulse (small duty) for TOF measurements [18,19].…”

High Detectivity Near Infrared Organic Photodetectors Using an Asymmetric Non-Fullerene Acceptor for Optimal Nanomorphology and Suppressed Dark Current

“…Solution-processable organic photodetectors (OPDs) have attracted interest because of their potential to replace conventional inorganic semiconductor-based photodetectors (PDs) and fabricate low-cost flexible image sensors. − Particularly, near-infrared (NIR) OPDs responding to approximately 750–1400 nm light are of great interest due to potential applications in optical communication, night vision, light detection and ranging (LiDAR), and health-monitoring devices. − The spectral range of NIR light absorption has been substantially extended through device architecture optimization , and the development of low-bandgap ( E g ) conjugated organic molecules (COMs) − or conjugated polymers (CPs). − However, the successful demonstration of NIR OPDs still faces a major challenge in developing high NIR-photon-to-electron conversion efficiency at λ > 900 nm, which is the desired wavelength for operating NIR devices, including LiDAR systems . Furthermore, as E g decreases for NIR light-absorbing materials, the dark current increases, significantly reducing OPD performance (such as low detectivity). ,,, Thus, organic materials with both high absorption coefficients at >900 nm and low dark current for practical NIR OPD applications should be developed.…”

Dual-Wavelength Polarization Independent Grating Coupler Design Based on Silicon-on-Insulator

“…Other than applications in the area of communication, silicon photonics is also widely used in sensing area, such as gas-sensing and bio-sensing. More importantly, the LiDAR (Light Radar) area has a great development potential [4]. Depending on the wavelength, LiDAR is used for different purposes such as facial recognition, autonomous cars, airborne surveying, and aerospace.…”

“…4 shows the incident angle versus the grating period length for both polarizations of 1310 nm and 1550 nm. It is calculated based on an initial condition for a 220 nm SOI platform with 0.5 fill-factor for both the x-and y-axis.…”