October 2006 University of Sharjah Journal of Pure & Applied Sciences Volume 3, No. 3 1 FABRICATION OF Pb X S 1-X FILMS PHOTOCONDUCTIVE DETECTORS M.F.A. Alias # , E.M.N. Al-Fawade # , A.A. Alnajjar* and A.A.J. Al-Douri* # Physics Department, Science College, University of Baghdad, Baghdad, Iraq * Basic Science Department, Arts and Science College, University of Sharjah Sharjah, United Arab Emirates ABSTRACT A polycrystalline Pb x S 1-x alloys with various Pb content (0.50, 0.51, 0.52, 0.54 and 0.55) have been prepared successfully. A photoconductive detector Pb x S 1-x film has been fabricated by depositing 1.5µm of Pb x S 1-x on Si (n- type) substrate with (111) direction by flash thermal evaporation at different x content and annealing temperature (T a ). Photoconductive properties, I-V characteristic, Spectral Response (R λ ), Quantum Efficiency ( η), Noise Equivalent Power (NEP), Specific Detectivity (D*), and time constant have been studied. The study of detector parameters exhibited two peaks for spectral , quantum efficiency and specific detectivity Keywords: Photoconductive Pb x S 1-x detector, photoconductive parameters. ﺔλϼΨϟ ا ﻚ΋ ﺎΒγ ﺎح ﺠϨΑ و ﺮتπΣ Pb x S 1-x ص ﺎλ ﺮϟ اϦϣ ﺔϔϠΘΨϣ ΐδ Ϩ Α و) 0.50 ، 0.51 ، 0.52 ، 0.54 ، 0.55 ( ﻬﺎϨϣﺔϴθ ﻏ أﺮϴπΤ Η ϢΗ وﺮϴΨΒΘϟ اﺔϘϳ ﺮτ Α ري ا ﺮΤ ϟ اϲπ ϴ ϣ ﻮϟ ا وϒη ﺎ آϊϴϨμΘ Α ﺎϨϤϗ Ϣ ﺛ، ﻬﺎμ ΋ ﺎμΧ ﺔγ ادرΖϤ Η ) β ﺠϣ ( Ϟ ϴ λ ﻮΘϟ ا ﻮعϧ Ϧϣ س ﺎδΣ - ϲ΋ ﻮπ ϟ ا. Ϙϴϗ رﺔϘΒσ ΐϴγ ﺮΗ ﺔτγ ا ﻮΑβ ﺠϤ ϟ اϊϴϨμΘ Α ﺎϨϤϗ ﻜﻬﺎϤγ ﺔ1.5 ﺮΘϣ ﻜﺮوϳ ﺎϣ ﺔϴθ ﻏ أϦϣ Pb x S 1-x ﺔϴϠϴλ ﻮΘϟ ا ﻮعϧ Ϧϣ ﻜﻮنϴϠδϟ اϞλ ﻮϣϪΒηϦϣ ﺔϳ ﻮرϠΑ ﺔϗ ﺎϗ رﻰϠ ϋ n- وذي ﻮريϠΒϟ اϩ ﺠﺎΗϻ ا) 111 .( ϞϤθΗ ﺔϔϠΘΨϣ ﺎت ﺠϟ ﺎόϤΑ β ﺠϤ ϟ اϊϴϨμΗ ϢΗ : 1 - ص ﺎλ ﺮϟ اϦϣ ﺔϔϠΘΨϤ ϟ اΐδ Ϩ ϟ ا) x ( 2 - ﺔϳ ار ﺮΣ ﺎت ﺠϟ ﺎόϣ ) Ϧϳ ﺪϠΗ ( ﺔϔϠΘΨϣ . κ ΋ ﺎμΧ وﺔΑ ﺠﺎΘγ ا ﺎرΒΘΧ اϢΗ ﺎϤ آϒη ﺎ ﻜϟ ا) β ﺠϤ ϟ ا( و ﺔϴ΋ ﻮπ ϟ اﺔϴϠϴλ ﻮΘϟ اϪμ ΋ ﺎμΧ ﺎسϴϘΑ ﺎرϴΗ – ϊϨμϤ ϟ اβ ﺠϤϠϟ ﺔϴϔθ ﻜϟ ا ﺪرةϘϟ وا ﺎءο ﻮπ Ϡ ϟ ﺔΌϓ ﻜﺎϤϟ ا ﺪرةϘϟ واﺔϴϤ ﻜϟ ا ﺎءةϔ ﻜϟ واﺔϴϔϴτϟ اﺔΑ ﺠﺎΘγϻ ا وﺔϴΘϟ ﻮϓ . 1. INTRODUCTION The need for high speed un-cooled detector ignited the research on narrow band gap compound semiconductors. High-speed un-cooled infrared (IR) detectors from PbS system are in high demand for many