Study Of The Radiation And Thermal Transmission Performance Of PbTe Thermoelectric Material

Lead telluride (PbTe) is a kind of very important Ⅳ-Ⅵ family narrow band gapsemiconductor compound, the forbidden band width is only0.31eV, and and refractive index ashigh as5.5, it has unique optical, electronic and chemical properties, is used to make the solarcell, infrared detector, light scattering detector and3-30μm range of semiconductor laserapplications. In this paper, the different thickness of PbTe films were fabricated on Si(111)substrate, then the different thickness of the Ag/Cu reflection films were deposited onto the samethickness of the PbTe films, and we studied the effect of the thickness of the film on the samplesof crystallization properties, surface morphology, transmittance and resistivity; Ag/PbTe filmswere prepared and then annealed, the effect of annealing temperature and annealing time on thecharacteristics of the films were investigated. The main research results are as follows:1. The Ag/PbTe films were deposited by magnetron sputtering and vacuum evaporation thenannealed in the annealing furnace. The effect of annealing temperature and annealing time on oncrystallization properties, surface morphology, transmittance and resistivity of the films wereinvestigated. The research results are as follows:(1) Under the different annealing temperature annealing20min. The experimental resultsshow that with the increase of annealing temperature, the crystallization properties of thesamples declined first and then improved; the surface of the sample become flat firstly, thensomething like island and some black flower gatherings appear on the face of the sample; thetransmittance of the thin film increase first and then reduce; the film resistivity decreases rapidlyand then slowly.(2) It is annealed by different annealing time while the annealing temperature is980℃. Withthe extension of annealing time, the crystallization properties of the samples improved first andthen worsen; some black flower gatherings appear on the face of the sample and the area of themincrease gradually, finally tend to disappear; the transmittance of the thin film reducesignificantly then increase; the film resistivity present first decimated and then have a small rebound trend.2. We deposit the different thickness of PbTe films by vacuum evaporation, then we deposit thedifferent thickness of the Ag/Cu reflection films onto the same thickness of the PbTe films, studythe effect of the film thickness and reflection film thickness on crystallization properties, surfacemorphology, transmittance and resistivity of the films. Research shows that:(1) The different thickness of PbTe films have strong (200) optimizing orientation andpolycrystalline structure. With the increase of film thickness, the film grain size, crystalproperties and surface roughness increase, the infrared absorption performance enhancements,resistivity decreased linearly. We can obtain the best performance film at3.5microns filmthickness.(2) The Ag/PbTe/ITO film system had strong (200) optimizing orientation direction andhad polycrystalline structure. FTIR transmission spectra present a few absorption peaks whichwere non-characteristic absorption peak of the PbTe, the analysis results showed these absorptionpeaks was due to the interference at both the top interface and the bottom interface of the PbTelayer. The transmittance reduced with the increase of the Ag reflecting film thickness, when thefilm exceeded a certain thickness range, the transmittance reduced to zero. The resistivitydropped rapidly in the initial part of the curve, then flat trend with the increase of the thicknessof the Ag reflecting film.(3) The Cu/PbTe/ITO film system had polycrystalline structure. With the increase of Cufilm thickness, the infrared absorption properties showed enhanced then weakening trend, whenCu reflection film thickness of10nm, the infrared absorption properties of thin film is the best,the resistivity decrease slightly.(4) Comparison, add the appropriate thickness of the reflector makes the PbTe of infraredabsorption intensity is enhanced, the infrared absorption properties of the sample which with Agreflective film reflective film improved more obviously than the sample which with Cu reflectivefilm, in the experiment, the sample has the best infrared absorption properties when the Agreflection film thickness is30nm.