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Solar-blind (Be,Mg)ZnO Photodetectors (260-285 nm wavelengths)

Description:

OBJECTIVE: Develop ZnO based UV photodetectors for the solar-blind detection window of 265-280 nm for various military applications. DDESCRIPTION: The photoresponse of current solar blind detectors (SBDs) is not sufficient for many applications where UV light needs to be sensed. Solar blind photodetectors are specified to the 265-280 nm region of the ultraviolet spectrum and require greater than several hundred milliamps per watt of photoresponse to replace photomultiplier tubes (PMTs) or other semiconductor based SBDs. ZnO (zinc oxide) and its alloys, e.g. (Be, Mg)ZnO, are sought for application to high responsivity photodetectors. (Be,Mg)ZnO alloys have been reported by some groups for application in this regime [1]. Recent programs on SBDs include silicon carbide based APDs (avalanche photodiodes) and GaN based alloy SBDs which have not met the requirements for replacing PMTs. As a highly efficient photoluminescent material, ZnO holds promise for these requirements based on recent development of BeZnO and MgZnO alloys that include nanowires. PHASE I: Demonstrate (Be,Mg)ZnO semiconductor alloys of high optical quality with optical bandgap of approximately 280 nm for solar blind detection regime with wavelength cutoff>100 for solar blind window region. Also, demonstrate doping and contact formation needed for the complete UV photodetector. Absorption data, contact resistance data, and p-doping should be measured and included in reports. PHASE II: Develop high responsivity solar-blind photodetectors (265-280 nm) for military applications. Performance goals should be those to surpass current SBDs with approximate photoresponse of 200 mA/W. Approaches to be investigated could include standard p-n junction photodetectors or avalanche photodetectors. Solar blind photodetectors should be delivered to ARL for evaluation (after evaluation the photodetector(s) - one or more - may be returned if desired). Also, if photodetectors were developed in bands outside the 265-280 nm window they should be delivered for comparison - one in each cutoff wavelength band -<265 nm,<280 nm,<300 nm, etc. to 385 nm, every 20 nm interval. PHASE III DUAL USE APPLICATIONS: Military applications include UV non-line of sight (NLOS) optical communications, bio-warfare agent detection, missile detection from plume signatures, and other spectroscopic UV signatures. Dual-use (civilian) applications include biosensing and bio-agent detection, flame detection, determination of engine combustion efficiency, atmospheric ozone studies, and astronomical studies. REFERENCES: 1. L. Li, J. Lubguban, P. Yu, H. W. White, Y. Ryu; T. Lee,"ZnO p-n junction photodetectors,"CLEO'07. 2007 Conference on Lasers and Electro-Optics, 2007, 331-332. 2. J. L. Liu, F. X. Xiu, L. J. Mandalapu, Z. Yang,"P-type ZnO by Sb doping for PN-junction photodetectors,"Proceedings of the SPIE - The International Society for Optical Engineering, v 6122, 9 Feb. 2006, p 61220H-1-7 3. H. Shen, M. Wraback, C. R. Gorla, S. Liang, N. Emanetoglu, Y. Liu, Y. Lu,"High-gain, high-speed ZnO MSM ultraviolet photodetectors,"GaN and Related Alloys - 1999. Symposium (Materials Research Society Symposium Proceedings Vol.595), 2000, p 11.16.1-6. 4. H. Liu, D. Mcintosh, X. Bai, H. Pan, M. Liu, J. Campbell, H. Y. Cha,"4H-SiC PIN recessed-window avalanche photodiode with high quantum efficiency,"IEEE Photonics Technology Letters, v20, n18, Sept. 15, 2008, pp. 1551-1553. 5. Y. Ryu, T. Lee, J. Lubguban, H. White, Y. Park, C. J. Youn,"ZnO devices: photodiodes and p-type field-effect transistors", Applied Physics Letters, v 87, n 15, 10 Oct. 2005, p 153504-1-3.
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