Disclosed herein is a method comprising: forming a doped region of a semiconductor substrate by doping a surface of the semiconductor substrate with dopants; driving the dopants into the semiconductor substrate by annealing the semiconductor substrate; controlling doping profile of the doped region by repeating doping and annealing the semiconductor substrate; forming a first electrode on the semiconductor substrate, wherein the first electrode is in electrical contact with the doped region; forming an outer electrode arranged around the first electrode, wherein the outer electrode is electrically insulated from the first electrode.

A detector configuration that combines a plurality of elongated semiconductor photo-multiplier sensor strips coupled to a scintillator crystal block with a differential readout that will enhance the time resolution. This is permitted due to a reduction of electronic noise due to reduced cross talk and noise in the ground. In addition, the dead area is minimized and thus the efficiency of the photodetector is enhanced.

For each X-ray path through a tissue, numerous trials are conducted. In each trial, X-ray photons are emitted along the path until a Geiger-mode avalanche photodiode “clicks”. A temporal average—i.e., the average amount of time elapsed before a “click” occurs—is calculated. This temporal average is, in turn, used to estimate a causal intensity of X-ray light that passes through the tissue along the path and reaches the diode. Based on the causal intensities for multiple paths, a computer generates computed tomography (CT) images or 2D digital radiographic images. The causal intensities used to create the images are estimated from temporal statistics, and not from conventional measurements of intensity at a pixel. X-ray dosage needed for imaging is dramatically reduced as follows: a “click” of the photodiode triggers negative feedback that causes the system to halt irradiation of the tissue along a path, until the next trial begins.

A semiconductor photomultiplier (SPM) device is described. The SPM comprises a plurality of photosensitive elements, a first electrode arranged to provide a bias voltage to the photosensitive elements, a second electrode arranged as a biasing electrode for the photosensitive elements, a plurality of quench resistive elements each associated with a corresponding photosensitive element, a plurality of output loads each having a capacitive load operably coupled to a resisitive load in a parallel configuration between first and second nodes; each first node is common to one of the photosensitive elements and the corresponding quench element; and a third electrode coupled to the second nodes of the output loads to provide an output signal from the photosensitive elements. The outputs loads fully or partially correct an overshoot of an output signal on the third electrode.

A scintillation detector, including a scintillator that emits scintillation; a semiconductor photodetector having a surface area for receiving the scintillation, wherein the surface area has a passivation layer configured to provide a peak quantum efficiency greater than 40% for a first component of the scintillation, and the semiconductor photodetector has built in gain through avalanche multiplication; a coating on the surface area, wherein the coating acts as a bandpass filter that transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths; and wherein the surface area, the passivation layer, and the coating are controlled to increase the temporal resolution of the semiconductor photodetector.

A semiconductor device may include a plurality of single-photon avalanche diodes. The single-photon avalanche diodes may be arranged in microcells. Each microcell may be a split microcell with first and second independent microcell segments. Each microcell segment in the split microcell may have a respective single-photon avalanche diode that is coupled to an output line. The single-photon avalanche diode of each microcell segment may also be coupled to a respective resistor that is used to quench avalanches in the single-photon avalanche diode. Splitting the microcell may reduce the recovery time of each microcell. The segments of the split microcell may be positioned close together, even if susceptible to optical crosstalk. Intra-microcell isolation structures may be formed between the microcell segments. Inter-microcell isolation structures may be formed around a perimeter of the split microcell. The intra-microcell and inter-microcell isolation structures may be different.

An ionizing radiation detector includes a first common semiconductor substrate and a first plurality of single-photon avalanche diode (SPAD) microcell structures disposed at a top face of the first common semiconductor substrate. Each SPAD microcell structure includes a first semiconductor junction that is reverse-biased beyond a first breakdown threshold. The ionizing radiation detector may also include common anode and cathode connections to each of the SPAD microcell structures that operate as an output. The ionizing radiation detector may also include control circuitry connected to the SPAD microcell structures. The control circuitry may be configured to control biasing of the SPAD microcell structures and measure electrical characteristics of a signal provided on the output. Charge drift within the first common semiconductor substrate need not be inhibited from exciting more than one of the SPAD microcell structures of the first plurality of SPAD microcell structures by isolation barriers.

A Single-Photon Avalanche Diode (SPAD) device an active region configured to detect incident radiation, a first radiation blocking ring surrounding the active region, and a radiation blocking cover configured to shield part of the active region from the incident radiation. The radiation blocking cover is configured to define a second radiation blocking ring vertically spaced apart from the first radiation blocking ring. The SPAD device may include radiation blocking vias extending between the first and second radiation blocking rings.

Radiation source localization systems and related techniques are provided to improve the operation of handheld or unmanned mobile sensor or survey platforms. A radiation source localization system includes a logic device configured to communicate with a communications module and a directional radiation detector, where the communications module is configured to establish a wireless communication link with a base station associated with the directional radiation detector and/or a mobile sensor platform, and the directional radiation detector includes a sensor assembly configured to provide directional radiation sensor data as the directional radiation detector is maneuvered within a survey area.

A radiation dosimeter comprising a thermal micro-platform with a plurality of nanowires having phononic structures providing improved thermal isolation of the micro-platform. In embodiments, thermo-luminescent, MOS transistor and PIN diode sensors for x-ray, gamma, charged particles and neutron irradiation are disposed on the micro-platform. In a preferred embodiment the dosimeter is fabricated using a silicon SOI starting wafer.