Preparation,Post-treatment And Photoelectric Properties Of Doped PbSe Thin Films

In this thesis,doped PbSe thin films with well-crystallized quality,adjustable optical band gap and infrared-sensitivity were investigated as follows:(1)A series of Sn doped PbSe thin films were prepared by magnetron sputtering with variable parameters.The micromorphology,crystal structure and optical properties were analyzed.Photosensitive devices based on the films were fabricated,and their photoelectric properties were examined.It was found that the thin films possessed the best sensitivity,responsivity and stability to infrared,under the conditions of:sputtering power(P=60W),bias(V=50V),and substrate temperature(T=100℃).(2)Pb1-xAgxSe(x=0.03,0.06,0.09 and 0.12)thin films were prepared by chemical bath deposition at room temperature.The films are composed of uniform distributed grains,whose crystal structure,morphology,and optical properties are all ajustable.With increasing Ag concentration,the film growth mechanism transits from cluster to ion by ion.Both the crystal shape and size change.Meanwhile,the optical band gap(Eg)of the thin films linearly increase from 0.26 eV to 0.31 eV.(3)The Sn-doped-PbSe thin films were sensitized by means of oxygen ion implantation.After ion implantation,the PbSnO3 phase was detected in the films,though the preferred orientation is maintained.There are two chemical states for oxygen:the surface adsorbed one and the lattice one,indicating the incorporation of O atoms into the Sn-PbSe crystal lattice.In addition,ion implantation increases the films’resistance,improved the photosensitivity.And the photosensitivity recession was restricted,i.e.the durability with cycles was enhanced.(4)The in-situ sensitized Sn-PbSe thin films were prepared by introducing a certain proportion of oxygen gas during deposition.The preferred orientation of the films is in(200)plane.The films surface is worm-like structure.With increasing ratio oxygen in sputtering gas,the crystals agglomerates and the films densify.At the same time,the band gap first decreases from 0.124 to 0.087 eV,and then increases to 0.145 eV when O2:Ar=1:2.The results show that the photosensitivity of the devices are significantly improveed by in-situ oxygen sensitization.The films achieve the best sensitivity and the resistance change rate is 54.19%,when O2:Ar=1:3.