Paul Vu

Bio: Paul Vu is an academic researcher from Fairchild Semiconductor International, Inc.. The author has contributed to research in topics: Image sensor & Dark current. The author has an hindex of 7, co-authored 17 publications receiving 191 citations.

A 5.5Mpixel 100 frames/sec wide dynamic range low noise CMOS image sensor for scientific applications

Abstract: In this paper we describe a 55Mpixel 100 frames/sec wide-dynamic-range low-noise CMOS image sensor (CIS) designed for scientific applications The sensor has 65μm pitch 5T pixels with pinned photodiodes and integrated microlenses The 5T pixel architecture enables low noise rolling and global shutter operation The measured peak quantum efficiency of the sensor is greater than 55% at 550nm, the Nyquist MTF is greater than 04 at 550nm, and the linear full well capacity is greater than 35ke- The measured rolling and global shutter readout noise are 128e- RMS and 254e- RMS respectively at 30 f/s and 20°C The pinned photodiode dark current is less than 38pA/cm2 at 20°C The sensor achieves an intra-scene linear dynamic range in rolling shutter operation of greater than 86dB (20000:1) at room temperature In global shutter readout the shutter efficiency is greater than 1000:1 with 500nm illumination

Soft X-ray spectroscopy with sub-electron readnoise charge-coupled devices

Abstract: We demonstrate use of a charge-coupled device (CCD) with sub-electron readnoise performance as a non-dispersive X-ray spectrometer. The exceptionally low readnoise (0.9 electrons rms) was achieved by applying a floating gate output amplifier with 16 readouts per pixel. The soft X-ray quantum efficiency was enhanced over other front-side illuminated devices by using a novel thin-poly gate structure. The combination of sub-electron noise and good soft X-ray quantum efficiency have enabled us to detect photons in the EUV energy range (E

CCD/CMOS hybrid FPA for low light level imaging

Abstract: We present a CCD / CMOS hybrid focal plane array (FPA) for low light level imaging applications. The hybrid approach combines the best of CCD imaging characteristics (e.g. high quantum efficiency, low dark current, excellent uniformity, and low pixel cross talk) with the high speed, low power and ultra-low read noise of CMOS readout technology. The FPA is comprised of two CMOS readout integrated circuits (ROIC) that are bump bonded to a CCD imaging substrate. Each ROIC is an array of Capacitive Transimpedence Amplifiers (CTIA) that connect to the CCD columns via indium bumps. The proposed column parallel readout architecture eliminates the slow speed, high noise, and high power limitations of a conventional CCD. This results in a compact, low power, ultra-sensitive solid-state FPA that can be used in low light level applications such as live-cell microscopy and security cameras at room temperature operation. The prototype FPA has a 1280 x 1024 format with 12-um square pixels. Measured dark current is less than 5.8 pA/cm 2 at room temperature and the overall read noise is as low as 2.9e at 30 frames/sec.

Low-Light-Level CMOS Image Sensor For Digitally Fused Night Vision Systems

Abstract: In this paper we present a VNIR solid state sensor technology suitable for next generation fused night vision systems. This technology is based on a highly optimized low power 0.18um CMOS image sensor (CIS) process. We describe a 320(H) x 240(V) pixel prototype sensor based on this technology. The sensor features 5T pixels with pinned photodiodes on a 6.5μm pitch with integrated micro-lens. The 5T pixel architecture enables both correlated double sampling (CDS) and a lateral anti-blooming drain. The measured peak quantum efficiency of the sensor is greater than 50% at 600nm, and the read noise is less than 1e- RMS at room temperature. The sensor does not have any multiplicative noise. The full well capacity is greater than 40ke-, the dark current is less than 3.8pA/cm2 at 20oC, and the MTF at 77 lp/mm is 0.4 at 600nm. The sensor also achieves an intra-scene linear dynamic range of greater than 90dB (30000:1) at room temperature.

Design of prototype scientific CMOS image sensors

Abstract: We present the design and test results of a prototype 4T CMOS image sensor fabricated in 0.18-µm technology featuring 20 different 6.5 µm pixel pitch designs. We review the measured data which clearly show the impact of the pixel topologies on sensor performance parameters such as conversion gain, read noise, dark current, full well capacity, non-linearity, PRNU, DSNU, image lag, QE and MTF. Read noise of less than 1.5e- rms and peak QE greater than 70%, with microlens, are reported.

Recent Progress and Future Prospects of 2D-based Photodetectors

Abstract: Conventional semiconductors such as silicon and InGaAs based photodetectors have encountered a bottleneck in modern electronics and photonics in terms of spectral coverage, low resolution, non-transparency, non-flexibility and CMOS-incompatibility. New emerging 2D materials such as graphene, TMDs and their hybrid systems thereof, however, can circumvent all these issues benefitting from mechanically flexibility, extraordinary electronic and optical properties, as well as wafer-scale production and integration. Heterojunction-based photodiodes based on 2D materials offer ultrafast and broadband response from visible to far infrared range. Phototransistors based on 2D hybrid systems combined with other material platforms such as quantum dots, perovskites, organic materials, or plasmonic nanostructures yield ultrasensitive and broadband light detection capabilities. Notably the facile integration of 2D-photodetectors on silicon photonics or CMOS platforms paves the way towards high performance, low-cost, broadband sensing and imaging modalities.

Characterization and Calibration of the CheMin Mineralogical Instrument on Mars Science Laboratory

Abstract: A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Mars-year nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5∘ to 50∘ 2θ with 13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar® or Kapton® windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstration-model (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations.

Filter-Free Image Sensor Pixels Comprising Silicon Nanowires with Selective Color Absorption

Abstract: The organic dye filters of conventional color image sensors achieve the red/green/blue response needed for color imaging, but have disadvantages related to durability, low absorption coefficient, and fabrication complexity. Here, we report a new paradigm for color imaging based on all-silicon nanowire devices and no filters. We fabricate pixels consisting of vertical silicon nanowires with integrated photodetectors, demonstrate that their spectral sensitivities are governed by nanowire radius, and perform color imaging. Our approach is conceptually different from filter-based methods, as absorbed light is converted to photocurrent, ultimately presenting the opportunity for very high photon efficiency.

Recent Progress and Future Prospects of 2D-Based Photodetectors

Abstract: Conventional semiconductors such as silicon- and indium gallium arsenide (InGaAs)-based photodetectors have encountered a bottleneck in modern electronics and photonics in terms of spectral coverage, low resolution, nontransparency, nonflexibility, and complementary metal-oxide-semiconductor (CMOS) incompatibility. New emerging two-dimensional (2D) materials such as graphene, transition metal dichalcogenides (TMDs), and their hybrid systems thereof, however, can circumvent all these issues benefitting from mechanically flexibility, extraordinary electronic and optical properties, as well as wafer-scale production and integration. Heterojunction-based photodiodes based on 2D materials offer ultrafast and broadband response from the visible to far-infrared range. Phototransistors based on 2D hybrid systems combined with other material platforms such as quantum dots, perovskites, organic materials, or plasmonic nanostructures yield ultrasensitive and broadband light-detection capabilities. Notably the facile integration of 2D photodetectors on silicon photonics or CMOS platforms paves the way toward high-performance, low-cost, broadband sensing and imaging modalities.