Lect11_notes

10 back scattered electron detectors solid state

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Unformatted text preview: Detector! •  20 keV – copper • Energy loss sequence: • Purple • Red • Magenta • Green • Blue • Black •  Consider a conventional BS imaging situation • Beam enters sample • Multiple specimen interactions result in gradual loss of energy in primary beam electrons • At any time, these electrons can exit sample surface and be detected • As Z increases, so does likelihood of a scattered electron exiting sample surface • (An x-ray excitation event will cause a larger energy drop in primary beam electron) •  Modeled with a David Joy Monte Carlo Simulation • Consider ten electrons CBEMS 164 – XRD, SEM & Microanalysis: Lecture 11 ! 10 Back-Scattered Electron Detectors – Solid State Devices! ! ! ! ! ! ! •  Principle –  Energetic electrons excite electron-hole pairs in intrinsic semiconductor –  Typically 2-4 times more BS electrons than SE electrons •  Always a BS component in an SE image –  Thin geometry allows close physical placement to specimen •  Energy needed ~3.6 eV –  Each incident 10 KeV...
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This note was uploaded on 01/16/2014 for the course CBEMS 164 taught by Professor Porter,j during the Fall '08 term at UC Irvine.

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