ELECTRON DETECTOR DEVICE FOR SPECTROSCOPIC ANALYSES OF SURFACES UNDER X-RAY EXCITATION

摘要

This invention concerns an electron detector device for spectroscopic analyses of surfaces under monochromatic X-ray excitation, this detector comprising: (i) a silicon diode (9) which is able to detect with a gain ？ 1 accelerated secondary electrons; (ii) a microchannel plate (5) to pre-amplify the conversion photoelectrons emitted by the sample (1), and which is used at extremely low gain but with excellent linearity characteristics. The key component is a cooled Si-diode made of high resistivity n-type silicon with an ion implanted p+ layer (11) which is about 1300 ？ thick. Its performances in detecting energetic electrons result from the absence of additional dead layers (passivated SiO？2? or protective aluminium coating), only a few aluminium strips (14) being designed to optimize the charge collection. A different method exploiting the excellent performances of this detector but requiring two successive scans, allows to discriminate the contribution of the surface sensitive conversion photoelectrons against the radiative contribution, i.e. that of the X-ray fluorescence emission which contains structural information on the bulk sample.