Radiation converter comprising a directly converting semiconductor layer and method for producing such a radiation converter

Abstract

A radiation converter 1 includes a directly converting semiconductor layer 2, wherein the semiconductor layer 2 includes grains 3 whose interfaces 4 at least predominantly run parallel to a drift direction-constrained by an electric field-of electrons liberated in the semiconductor layer 2. In at least one embodiment, the charge carriers liberated by incident radiation quanta are accelerated in the electric field in the direction of the radiation incidence direction 10 and on account of the columnar or pillar-like texture of the semiconductor layer 2, in comparison with the known radiation detectors, cross significantly fewer interfaces 4 of the grains 3 that are occupied by defect sites. This increases the charge carrier lifetime / mobility product in the direction of charge carrier transport. Consequently, it is possible to realize significantly thicker semiconductor layers 2 for the counting and / or energy-selective detection of radiation quanta. This increases the absorptivity of the radiation converter 1 which in turn makes it possible to reduce a radiation dose applied to the patient. At least one embodiment of the invention additionally relates to a method for producing such a radiation converter 1.

Description

technical field [0001] The invention relates to a beam converter with a directly converting semiconductor layer. Furthermore, the invention relates to a method for producing such a beam converter. Background technique [0002] A beam converter with a direct-converting semiconductor layer enables a counted and / or energy-selective detection of individual quantum absorption events entering the semiconductor layer through the detection surface. In this case, radiation quanta, for example gamma-ray quanta or X-ray quanta, are absorbed in the semiconductor layer and converted into free charge carriers. These released carriers are accelerated in the electric field generated by the voltage applied between the counter electrode and the pixelated read electrode. The associated charge carrier transport in the semiconductor layer induces a current at the read electrode, which current is tapped by the read circuit and recorded as an electrical signal. [0003] The conversion of the ra...

AI Technical Summary

Problems solved by technology

[0005] Quantitative and energy-selective acquisition is limited due to defect sites (Defektstellen) generated in the lattice by the manufacturing process, e.g. in the form of vacancies or interlattice atoms

These defect sites are responsible for the polarization effect that leads to a decrease in the carrier lifetime mobility product (μτ product) and thus to an increase in the average residence time of carriers in the semiconductor material while reducing their lifetime

This reduces the separation efficiency of the released carriers

In particular, there is the risk that the signal is covered by quanta incident densely in time one after the other, making it impossible to uniquely separate the events

But the released carriers can also completely recombine with existing, oppositely charged defect sites, so that these carriers are completely lost in the conversion to an electrical signal

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