A 512/spl times/512-element, multi-frame charge-coupled device (CCD) has been developed for collecting four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity, the imager uses an electronic shutter technology developed for back-illuminated CCDs. The megahertz frame rates also required metal strapping of the polysilicon gate electrodes. Tested imagers have demonstrated multi-frame capture capability.

Improved and stable blue/UV quantum efficiency has been demonstrated on 2K×4K imagers using molecular-beam epitaxy to create a thin doped layer on the back surface. Quantum efficiency data on thick (40–50 μm) imagers with single and dual-layer anti-reflection coatings is presented that demonstrates high and broadband response. Measurements of the optical point-spread response show the devices to be fully depleted with good response across a broad spectrum, but interesting features appear in the near-IR as a result of deeply penetrating light being scattered off the surface structure of the CCD.

A manufacturable process for converting a front-illuminated CCD imager to its back-illuminated counterpart is described. Low-light-level imaging is enhanced, especially in the blue and deep-ultraviolet region. Quantum efficiency is significantly improved by forming a shallow p+ accumulation layer on the back surface using a laser-induced activation of very-low-energy boron implantation. The fabrication process has been applied to 64-×128-, 420-×420-, and 420-×840-pixel imagers. An example of imaging obtained with the 420-×420-pixel imager is shown and discussed. Experimental results showing the enhanced response of the 64-×128-pixel imager are presented

Electronically shuttered solid-state imagers are being developed for high-speed imaging applications. A 5 cm×5 cm, 512×512-element, multiframe charge-coupled device (CCD) imager has been fabricated for the Los Alamos National Laboratory DARHT facility that collects four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity, the imager uses an electronic shutter technology designed for back-illuminated CCDs. The design concept and test results are described for the burst-frame-rate imager. Also discussed is an evolving solid-state imager technology that has interesting characteristics for creating large-format x-ray detectors with short integration times (100 ps to 1 ns). Proposed device architectures use CMOS technology for high speed sampling (tens of picoseconds transistor switching times). Techniques for parallel clock distribution, that triggers the sampling of x-ray photoelectrons, will be described that exploit features of CMOS technology.

We report on the design of a system used to measure the multispectral intrapixel response of imaging sensor arrays. An Airy disk spot size of approximately 4 mu m has been achieved for wavelength bands that extend from the visible blue to near infrared. The automated system does rapid intrapixel row and/or column spatial mapping of individual pixels as well as rastered two-dimensional spatial scans over multi-pixel grids. Commercially available equipment including a photometric eyepiece, a reflective objective, programmable pushers, and light-emitting diodes (LEDs) (at various wavelengths from the near ultraviolet to the near infrared) are utilized in the system. Scanned results using the system are presented for both front- and back-illuminated charge-coupled device (CCD) imagers. The intrapixel response of a front-illuminated device shows good correlation with the physical cross section of the devices tested.

There have been many recent developments in the attributes and capabilities of silicon-based CCD detectors for use in space and ground-based astronomy. The imagers used as X-ray detectors require very low noise and excellent quantum efficiency over the energy range of 200-10 000 eV. This is achieved using a combination of front and back-illuminated imagers fabricated on a 5000 Omega-cm resistivity material. A requirement for ground-based imagers is very good sensitivity between 350 and 1000 nm, as well as low noise and a high degree of spatial uniformity. We will describe the fabrication and performance of these imagers. Special features integrated into the CCD pixel architecture have increased the capability of the imagers. A fast electronic shutter has been developed for a wavefront sensor in an adaptive optics system. An orthogonal transfer CCD has been designed to compensate for the image motion relative to the CCD focal plane. Also, an antiblooming drain process has been developed so bright sources do not extend spatially into adjacent pixels in back- and front-illuminated imagers. Aspects of the design, fabrication, and performance of imagers with these features will be described. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

We describe a back-illuminated 640/spl times/480 CCD imager which operates at 30-Hz frame rates with 5 e/sup -/ noise and which is capable of high resolution down to near starlight illumination levels. A new process for fabricating a compact blooming control is also described.

We describe recent work in the area of large, back-illuminated CCD imagers at M.I.T. Lincoln Laboratory as well as new technology applicable to astronomy. We completed in 1995 the development of a 2560 x 1960-pixel frame-transfer imager that filled a 100-mm wafer and several back-illuminated versions of this device were completed. More recently we have begun the development, in collaboration with the U. of Hawaii, of a three-side abuttable 2k x 4k CCD for a multi-chip focal plane. In the unused chord area of the wafer layout, we added test imagers as development vehicles for blooming control and for the demonstration of a CCD that is capable of charge transfer in all four directions. We expect the latter to find application as an electronic means of performing tip-tilt correction to compensate for atmospheric turbulence.

High-sensitivity, low-noise, and high-frame-rate charge-coupled-devices (CCD) and camera system electronics have been developed for imaging applications in the visible and near infrared spectra. Back-illuminated CCD imagers are used in the camera system for sensitive signal detection. A fabrication technology, using a refractory process, has been developed for CCD back-illumination that has quantum efficiencies as high as 90% from 500 to 700 nm and 50% from 200 to 400 nm. The CCD imagers use multiple output ports, with single-port pixel rates up to 5 MHz, for low-noise operation at high frame rates. An electronic shutter has been integrated into the pixel structure that has switching times of approximately 50 ns and an extinction ratio value of 104 (signal detected shutter opened to shutter closed) at wavelengths below 540 nm. A flexible electronic board set, providing various operating modes, has been designed to run the CCD at high frame rates while maintaining the detection sensitivity of the imager.

A charge modulation device (CMD) has been fabricated in a p-type epitaxial layer grown from the buried-channel silicon region of a charge-coupled device (CCD). Construction of the CMD directly above the CCD buried-channel and over the oxidized CCD transfer gates lowers the effective sense capacitance while providing isolation of the CMD source/drain regions. Responsivity values of 28 and 66 /spl mu/V/e for feedback and no feedback conditions, respectively, were measured dynamically on test devices. Input-referred noise values of approximately four electrons r.m.s. were calculated from noise spectral density measurements assuming a low-pass filter 3 dB cutoff frequency of 5 MHz and correlated double sampling.