Silicon drift diode detector configured to switch between pulse height measurement mode and current measurement mode
AssigneeFEI Company
InventorsCornelis Sander Kooijman, Gerard Anne Nicolaas van Veen
Life of this patent
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Abstract
A detector with a Silicon Diode and an amplifier, and a feedback element in the form of, for example, a resistor or a diode, switchably connected to the output of the amplifier. When the feedback element is selected via a switch, the detector operates in a Current Measurement Mode for determining electron current, and when the element is not selected the detector operates in its well-known Pulse Height Measurement Mode for determining the energy of X-ray quanta.
Claims14
A radiation detector for detecting X-rays and electrons incident on a surface, the detector comprising a Silicon Drift Diode,
- a voltage/current converter between an I/O port and the anode, a switch configured to selectively connect the voltage/current converter, as a result of which the Silicon Drift Diode is equipped to switchably operate in a pulse height measurement mode or a current measurement mode,
- a surface sensitive to radiation disposed opposite to a surface on which the anode is formed,
- an active volume close to the surface sensitive to radiation, a distance of the active volume to the surface sensitive to radiation sufficiently small for electrons with an energy as low as 20 keV to penetrate to the active volume and generate electron/hole pairs in the active volume,
- as a result of which the detector can selectively be used as a detector for detecting X-rays incident on the surface in the pulse height measurement mode or as a detector for detecting electrons incident on the surface in the current measurement mode.
A Silicon Drift Diode for detecting X-rays and electrons, comprising:
- an anode and an output, the Silicon Drift Diode producing a pulse on the output in response to a single detected photon, the output connected to electronic circuitry for measuring an output signal;
- a voltage/current converter between an I/O port and the anode;
- a feedback loop controlled by a switch, as a result of which the Silicon Drift Diode is equipped to switchably operate in a pulse height measurement mode for detecting x-rays or a current measurement mode for detecting electrons;
- an outer surface sensitive to radiation;
- and
- an active volume configured to generate electron-hole pairs when impinged upon by a radiation,
- wherein a distance from the active volume to the outer surface is small enough that electrons with energies of 20 keV irradiating the outer surface can penetrate to the active volume and generate electron/hole pairs in the active volume, and
- wherein the Silicon Drift Diode is configured to detect electrons penetrating the active volume during operation of the Silicon Drift Diode in the current measurement mode.
Dependencies are inferred from the claim text.