| 摘要 |
<p>The invention relates to a detector with a Silicon Drift Diode (SDD) ( 10 , 200) for use in a charged particle apparatus. Such detectors are well-known for the detection of X-rays, but are not capable to detect secondary or backscattered electrons for two reasons:
1. the volume (20) in the SDD where electron/hole pairs must be generated is too far removed from the surface ( 18 ). This can be solved by known techniques resulting in a shallow layer, for example using thin boron layers.
2. Secondary and/or backscattered electrons are generated with a much higher efficiency than X-rays, as a result of which the current of backscattered electrons is typically too high to be detected due to the limited count rate of a SDD (typically up to 1 Mc/s, equivalent to a maximum electron current of up to 0.16 pA). The invention describes a detector with a SDD ( 200 ) and an amplifier (206), and a feed-back element in the form of, for example, a resistor (208) or a diode, switchably connected to the output of the amplifier. When the feedback element is selected via a switch (209), 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.</p> |
