Abstract: A large area deep-diffused phototransistor having a photosensitive area of at least 1 mm.sup.2, and typically 25 mm.sup.2 or larger includes a light entry layer of a deep-diffused p type semiconductor material; at least one well of an n type semiconductor material that is disposed in contact with the light entry layer so as to form a first p-n junction therebetween; and a respective readout contact comprising a p type semiconductor material that is disposed in the n type well so as to form a second p-n junction. The p type material light entry layer, the n type material well, and the p type material readout contact respectively comprises the collector, base and emitter of the phototransistor. The concentration of the p type dopant in the deep diffused light entry layer has a positive gradient extending from the first p-n junction towards the surface of the light entry layer such that the concentration of the p type dopant is greater the closer the proximity to that surface.

Abstract: A method of forming a planar photosensitive device, such as an array of APDs, includes the steps of doping a substantially planar block of n type semiconductor material with a p type dopant in accordance with a selected pattern to form a plurality of p type wells in the block surrounded by a foundation of n type semiconductor material. Each p type well corresponds to an APD pixel and is disposed so as to respectively adjoin a first surface of the block and such that a respective p-n junction is formed between the p type material in the well and the n type material foundation. Each APD pixel further comprises depletion layer profile modification means such that the peak surface electric field of the p-n junction in each well is substantially less than the bulk electric field of the same p-n junction.

Abstract: A method of forming a planar semiconductor device, such as an array of APDs, includes the steps of doping a substantially planar block of n type semiconductor material with a p type dopant in accordance with a selected pattern to form a plurality of n type wells in the block surrounded by a foundation of p type semiconductor material. Each n type well is disposed so as to respectively adjoin a first surface of the block and such that a respective p-n junction is formed between the n type material in the well and the p type material foundation. The n type semiconductor material in each well has a substantially constant concentration of n type dopant throughout the n type material; the concentration of p type dopant in the foundation has a positive gradient extending from the p-n junction towards the second surface such that the peak surface electric field of the p-n junction in each well is less than the bulk electric field of the same p-n junction.

Abstract: A planar photosensitive device, such as an array of APDs, includes a planar block of n type semiconductor material having a plurality of p type wells in the block surrounded by a foundation of n type semiconductor material. Each p type well corresponds to an APD pixel and is disposed so as to respectively adjoin a first surface of the block and such that a respective p-n junction is formed between the p type material in the well and the n type material foundation. Each APD pixel further comprises depletion layer profile modification means such that the peak surface electric field of the p-n junction in each well is substantially less than the bulk electric field of the same p-n junction.

Abstract: A radiation detection device includes a scintillator having an upper scintillator body section and a lower scintillator body section. The upper section forms an arcuate-shaped cap through which the incident radiation enters the scintillator, and the lower section has sidewalls disposed at a selected taper angle with respect to the longitudinal axis of the scintillator body and an optically transmissive window disposed opposite the cap of the upper section such that optical photons can pass from the scintillator to a photodetector coupled to the window. An optically-diffuse reflective layer is disposed over the sidewalls and the cap. The sidewalls typically have a positive taper angle, being closer to one another near the optically transmissive window and farther from one another near the cap. The arcuate shape of the cap typically conforms to the arc of a circle centered on the optically transmissive window.