The Study On 4H-SiC Doped With The Fifth Period Transition Metal Based On The First Principles

In recent years,the integration of electronic devices has been continuously improved.The traditional semiconductor integrated circuit is gradually limited by quantum effect,which resulted bottlenecks in processing,transmitting and storing information.However,spintronics devices,which have both the charge and spin properties of electrons,have the characteristics of low energy consumption,high speed,small size and non-volatile,and can realize logic operation,sensing information and quantum computation of high-density data.Si C diluted magnetic semiconductors have potential applications for the field of the spintronics devices and become the focus on researchers'attention.Therefore,the study on Si C diluted magnetic semiconductors is of great significance.In this paper,the energy band structures,electronic state density,magnetic and optical properties of the fifth period transition metal element?Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag and Cd?doped 4H-Si C system are calculated and analyzed based on the first principles.Because 4H-Si C is a uniaxial hexagonal crystal,we study the effect of doping on the optical properties of 4H-Si C from the directions of vertical c-axis?100?and parallel c-axis?001?.The main conclusions obtained in this article are as follows:?1?The band gap value of intrinsic 4H-Si C is 2.28 e V.The value of Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag and Cd doped 4H-Si C are 1.47 e V,2.23 e V,1.87 e V,0.55 e V,0.07 e V,0.81 e V,0.99 e V,0.70 e V,1.47 e V and 1.27 e V,respectively.Compared with the intrinsic state,the band gap values of doping systems are all reduced in some degree,because the impurity energy levels are introduced by doping.Among the 10 doping systems,Y,Zr,Tc,Rh,Pd,Ag,and Cd doped4H-Si C systems are p-type doped,Nb and Ru are n-type doped,and Mo doped system exhibits semi-metallic property.?2?The up-spin state electrons and down-spin state electrons of Y,Mo,Tc,Rh,Pd,Ag and Cd doped 4H-Si C are asymmetric.Because the energy level splitting occurs and forming a local spin magnetic moment near the fermi energy level,which make the doping system magnetic.However,Zr,Nb,Ru-doped4H-Si C show no magnetism.?3?The static dielectric constants of Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag and Cd single-doped 4H-Si C are all greater than the intrinsic 4H-Si C,and the low energy boundaries of dielectric dissipation occur red shift.Zr-doped 4H-Si C is similar to the intrinsic 4H-Si C;The₂??of Nb,Mo,Ag and Cd doped systems have double peaks in the direction of?100?and?001?,while Rh and Pd have three peaks;Y-doped 4H-Si C system appears double peaks in the direction of?100?and single peak in the direction of?001?;Tc-doped system has three peaks in the direction of?100?and two peaks in the direction of?001?;Ru-doped system presents bimodal in the direction of?100?.?4?Mo,Zr,Nb,Tc and Ru doped 4H-Si C have a weak absorption peak at short wave compared with the intrinsic 4H-Si C.The absorption peak positions of Y,Zr and Nb doped are red shift.Mo,Tc,Ru,Rh,Pd,Ag and Cd doped showed blue shift,and the doping absorption interval extended to the direction of long wavelengths;In the directions of?100?and?001?,the maximum energy loss peaks of Y,Mo,Zr,Nb and Cd doped 4H-Si C are red shift,while the maximum energy loss peaks of Ru and Rh doped systems are blue shift.The maximum energy loss peaks of Tc,Pd and Ag are red shift in the direction of?100?and blue shifted in the direction of?001?;In the direction of?100?,the reflection peak of Y,Mo,Tc,Ru,Rh,Pd,Ag and Cd doped system are blue shift,Zr and Nb doped system are red shift.In the direction of?001?,the reflection peaks of Y,Mo,Zr,Nb doped systems are red shift and Tc,Ru,Rh,Pd,Ag doped systems are blue shift.