New Technology EDS Detectors for X-ray Microanalysis

The goal of the proposed work is to develop a novel detector for analytical spectrometry having large active area, high-energy resolution and capable of operating at high counting rates. The proposed detector will be specifically designed for x-ray microanalysis to provide orders of magnitude advancement in the performance over conventional energy dispersive systems. During the Phase 1 effort of this project, we successfully designed, fabricated, and demonstrated a ~2cm2 silicon drift detector (SDD) array. All of the goals of Phase 1 were met, and most were significantly exceeded. Accomplishments included development of a closely spaced array of four 0.5 cm2 SDD elements. Energy resolution of 143 eV FWHM at 5.9 keV was achieved on the best device. All four devices produced energy resolution below 200 eV FWHM. Importantly, these results were obtained at relatively short peaking times and additionally the detectors do not require cryogenic cooling to obtain this performance. In Phase 2, we will develop a prototype x-ray spectrometer for insertion into an electron microscope. The prototype will include the finalized detector array of up to four elements based upon the Phase 1 study. Each element will be capable of attaining electronic noise of <10 e- rms at peaking times on the order of 100 ns, allowing throughput rates exceeding 106 cps each. These advances will have a remarkable impact on reducing the acquisition time for 2-dimensional compositional mapping. The prototype system will be deployed for evaluation at NIST in one of the scanning electron microscope instruments.