J. M. Killiany

Infrared focal plane array technology

Requirements for infrared focal plane arrays (IRFPAs) for advanced infrared imaging systems are discussed, and an overview is given of different IRFPA architectures. Important IR detector structures, including photoconductive, photovoltaic, metal-insulator-semiconductor (MIS), and Schottky barrier, are reviewed. Infrared detector materials and related crystal-growth techniques are discussed, emphasizing applicability to IRFPA designs and performance. Three types of input circuit used to couple the detector to the readout circuitry are discussed, namely, direct injection, buffered direct injection, and gate modulation. An overview is given of several readout techniques, including the CCD, MOSFET switch, CID, and CIM. Also discussed are related onchip signal processing topics as well as questions regarding producibility and array implementation. >

Radiation Effects on Silicon Charge-Coupled Devices

The permanent ionizing and neutron radiation-induced degradation in silicon charge-coupled devices, (CCDs), along with transient upset effects, are reviewed. The operation of a threshold voltage insensitive CCD input technique in a total dose radiation environment is evaluated. CCD structural design rules for decreasing ionizing radiation sensitivity are presented. The increased total ionizing dose tolerance of CCDs fabricated with a radiation hard oxide is described. Liquid nitrogen temperature irradiation effects in CCDs are discussed.

Effects of ionizing radiation on charge-coupled device structures

The effects of ionizing radiation on four different charge-coupled device structures have been investigated. Both shift registers and optical imaging devices have been considered. The electrical and imaging (where appropriate) performance of the devices were evaluated as a function of total gamma ray dose. The principal failure mechanisms have been identified for each particular device structure. Some conclusions about the relative radiation tolerance of the various device designs are drawn.

A Radiation Hard MNOS CCD for Low Temperature Applications

P-buried channel charge-coupled devices (CCDs) with a 100 Å sio2 and 1.2 Å Si3N4 dual gate insulator have been fabricated and radiation tested. The CCDs are 105-and 150-bit 4-phase linear shift registers with double-level polysilicon gates. Most of the experimental data is obtained on p-buried channel devices because design considerations suggest that the p-buried channel structure will have the greatest tolerance to ionizing radiation for devices with MNOS gates. Threshold shifts on the order of -1 volt/106 rad(Si) have been achieved at both 80°K and 300°K on CCDs which are operated continuously during the irradiation. The p-buried channel CCDs show essentially no degradation in pre-irradiation transfer efficiency up to doses of 106 rad(Si) without any change in the operating biases.

Infrared Focal Plane Array Technology Development For Navy Applications

This paper discusses the Navy program for infrared focal plane array (IR FPA) development as well as several ultimate IR FPA system applications. Of particular interest are applications involving missile seekers, threat warning, and search and track. Advantages of IR systems as Navy sensors are discussed, as are problems involved with developing high-performance IR FPAs. Emphasis is placed on specific IR FPA technologies currently being developed as part of the Navy program. These technologies include both hybrid and monolithic arrays (charge-coupled devices, charge-injection devices, and charge-imaging matrix devices). Other technologies are also discussed.

Effects of Ionizing Radiation on a 256-Stage Linear CCD Imager

The total dose effects of gamma radiation on an unhardened 256-stage linear CCD imager have been investigated. Key device parameters were monitored and the primary failure mechanisms identified. Additional structural design rules for radiation hard CCDs were formulated. The performance of a threshold insensitive input technique was evaluated.

Low-Temperature Radiation Damage Effects in a Room-Temperature Radiation-Hard Surface Channel CCD

Room temperature radiation hard p-surface channel CCDs were irradiated at 85°K with 2 MeV electrons while being operated as dynamic shift registers. The increased charge trapping in the oxide at liquid nitrogen temperatures produced an input gate threshold voltage shift of -5.6V at 4×104 rads as compared to a -2.2V shift after 1×106 rads at 300°K. Except for the input gate voltage, the devices could be operated with the pre-irradiation clock and bias voltages after receiving 4×104 rads. A 20% increase in the signal handling capacity was observed after 3×104 rads. The output source-follower gain increased by approximately 10% after 4×104 rads. The excess flat-band voltage shift and increased transfer inefficiency was annealed by warming the device to 300°K with all clock and bias voltages applied.

Effects of radiation on buried‐channel CCDs with doped polysilicon gates and undoped polysilicon interelectrode isolation

The effects of gamma radiation on the operation of a buried‐channel charge‐coupled device having doped polysilicon electrodes and undoped polysilicon interelectrode isolation were studied. Doses up to 1×104 rad caused no increase in the transfer inefficiency. At a dose of 3×104 rad, the flat‐band voltage shift was sufficient to drive the buried channel out of depletion and to cause field‐induced channeling in the undoped polysilicon isolation regions. Increasing the channel bias returned the channel to depletion. However, channeling of the isolation regions could not be eliminated by changing the clock and bias voltages.

Gamma Radiation Induced Noise in a CCD Imager

In this paper, measurements of gamma well filling and noise generation in 100 × 100 pixel CCD imagers with bulk and reduced photosite collection volumes will be reported. The measurements were made at dose rates from 1.5 to 35 rad(Si)/sec which produce signals from 8 to 90% of well saturation in the 0.1 sec integration time. The rate of well filling in the 9 to 12 micrometer thick devices was only 25% of that in the 200 micrometer thick bulk device. Noise values from 55 to 60 times the optical shot noise were measured in the thin devices and described using a previously developed noise model. A value of 35 was measured in the thick device. The lower than expected gamma induced noise in the thick device was modeled using a diffusion-recombination mechanism.

Effects of Ionizing Radiation on a 244 Line by 188 Element Charge Injection Device Imager

The total dose effects of gamma radiation on an unhardened 244 line by 188 element charge injection device (CID) imager have been investigated. Key device parameters were monitored and the primary failure mechanisms identified. The operating parameters which are compatible with the largest possible total dose tolerance were determined.