SOFT X-RAY SILICON PHOTODIODES FOR SYNCHROTRON RADIATION SURFACE ANALYSIS

SILICON P-N JUNCTION PHOTODIODES (AXUV DIODES) WITH STABLE, THEORETICALLY PREDICTABLE QUANTUM EFFICIENCIES IN THE SOFT X-RAY (1 TO 100 NM) WERE DEVELOPED BY US RECENTLY LEADING TO THEIR USE FOR THE ESTABLISHMENT OF AN INDEPENDENT RESPONSIVITY SCALE FOR THE SOFT X-RAY REGION. THE LARGEST ACTIVE AREA DIODE DEVELOPED SO FAR IS 3 CM(2) LIMITING THE SOLID ANGLES DURING SURFACE ANALYSIS STUDIES. FABRICATION OF A 10 CM(2) AREA AXUV DIODE WITH EXTREMELY LOW CAPACITANCE WILL BE FABRICATED DURING PHASE I RESEARCH FOR PHOTON DETECTION DURING XAS. THIS DIODE WILL BE BAKEABLE TO 200 DEGREES CENTRIGRADE AND WILL BE FABRICATED WITH VISIBLE LIGHT BLOCKING THIN FILM METALLIC FILTER TO LIMIT THE SOFT X-RAY PHOTON ACCEPTANCE BANDWIDTH. INVESTIGATIONS ON FABRICATION OF 1 CM(2) AXUV DIODE WITH A 1MM X 2MM SLIT IN THE CENTER FOR INCIDENT BEAM INTENSITY MONITORING DURING XAS EXPERIMENTS WILL ALSO BE CARRIED OUT DURING THE PHASE I RESEARCH. IF THE LARGE AREA DIODE IS FOUND TO BE USEFUL FOR THE FLUORESCENCE YIELD DETECTION, FABRICATION OF A STILL LARGER SOLID ANGLE DETECTOR WITH ASSOCIATED SIGNAL AMPLIFYING ELECTRONICS WILL BE PROPOSED DURING PHASE II RESEARCH.