| In this paper,an infrared detector based on the environment-friendly material higher manganese silicide（HMS）was developed.The photoelectric properties of HMS-based infrared detectors are investigated by theoretical calculations,simulations and experimental researches.The experiments are guided by sumulations,and the theoretical calculations are verified by experiments.The influence of different infrared detector structures on device performances are specifically analyzed,which provides a solid foundation for the practical application of infrared detectors.The results are as follows:1.The effects of Cr doping and Cr-Mo co-doping on the electronic structure and photoelectric properties of HMS were investigated by first-principles base on plane wave pseudopotential method.The results show that the bandgap widths of the intrinsic Mn4Si7,Cr-doped Mn4Si7 and Cr-Mo co-doped Mn4Si7 are 0.813 eV,0.730 eV and0.620 eV,respectively.The intrinsic HMS and doped Mn4Si7are quasi-direct bandgap semiconductors with p-type conductivity.In addition,The dielectric functions,refractive indexes,absorption coefficients,optical conductivities and reflectivities are stronger than the intrinsic Mn4Si7while the doped systems are in the low energy region.2.The bonding of HMS/Si interfacial atoms were investigated by first-principles based on plane wave pseudopotential method.The results demonstrate that the binding energy reaches the minimum,the interfacial structure of HMS/Si reaches to the most stable status while the interval between Si layer and HMS layer is 0.21 nm.The wide pseudo gap indicates a strong covalency of bonding between Mn-Si atoms and Si-Si atoms.Among then,Mn-Si atomic bonds have the largest overlap populations,the smallest atomic bond length and the strongest electron distribution at HMS/Si interface,which the stable covalent bonds can be formed.In addition,a built-in electric field with a direction from Si to HMS is generated at the HMS/Si interface.The formation of the built-in electric field is conducive to the separation of photoelectron-hole pairs.3.Several infrared detectors base on HMS were designed.The infrared detectors are modeled and device performance were investigated by Silvaco.The research results confirm that the HMS/n-Si infrared detectors have better rectification characteristics than the n-Si/HMS/n-Si infrared detectors,while the n-Si/HMS/n-Si infrared detectors have lower dark current under reverse voltage(The zero-bias dark current reaches7.30×10-6 A at 250 K),which means the n-Si/HMS/n-Si infrared detectors have better detection performance.In addition,n-Si/HMS/n-Si infrared detectors show better thermostability.4.The HMS films were deposited on n-type silicon substrates and characterized.The XRD spectra reveal that the sample has the weak Mn O diffraction peaks and Si diffraction peaks from the substrate,the other diffraction peaks are not offset,which can be well matched with the standard PDF cards.The SEM patterns demonstrate that the grains on the surface of the films are clearly visible,with similar grain size,uniform distribution and compact structure.There are no bumps and gullies on the surface,and no cracks or bare substrates in the growth of the sample.5.The electrical transport properties and Raman spectra of the prepared HMS/n-Si were tested and analyed.The results reveal that the carrier concentration of HMS is1.79×1021 cm-3,the Hall mobility is 2.05 cm2/V·s,the Hall coefficient is 0.1403 m2/C,the Hall resistivity is 1.75×10-3Ω·cm,the sheet resistance reaches 684.31Ω/sq,and the conduction type of HMS film is P-type,which can form P-N junction with n-Si substrate.In addition,the Raman spectra show that the sample has obvious Raman peaks of Mn27Si47 at 273 cm-1,297 cm-1 and 313 cm-1,and the background noise is very low.6.The HMS/n-Si infrared detector was prepared and its device performance was tested and analyzed.The I-V characteristics show the sample has a low dark current（The current magnitude reaches 0.49 m A at-6 V）and good rectification characteristics,the rectification ratio reaches 15.6,and the turn-on voltage is 0.4 V while the specific detectivity of the detector reaches 1.251×108cm·Hz1/2/W.7.Different structures of n-Si/HMS/n-Si infrared detectors were prepared,and the device performance was investigated.The infrared detectors with a thickness of 23 nm have extremely low dark current of 10-7 A,the turn-on voltage as low as 0.2 V,the rectification ratio as high as 546 while the specific detectivity of the detector reaches1.34×1012 cm·Hz1/2/W.In conclusion,compared with the HMS/n-Si infrared detectors,the infrared detectors of n-Si/HMS/n-Si have the device performances such as the dark current,turn-on voltage,rectification characteristics and specific detectivity are better than the infrared detectors with HMS/n-Si structure. |
