Design And Photoelectric Application Of Novel Semiconductor Materials Based On The Ⅳ Main Group

The structural design and physical properties of new materials have always been a hot topic in condensed matter physics.Silicon and other IV main group semiconductors play an important role in the field of optoelectronics and microelectronics due to their excellent properties.Their excellent electronic and optical properties especially make them have great development potential in the field of optoelectronic devices.However,the application of diamond silicon in the optoelectronics industry is limited due to its band gap.It is an ideal solution to optimize and transform silicon by means of allotrope and homologous element doping.Using the first principles calculation method based on quantum mechanics,eleven kinds of novel IV main group semiconductor materials are designed in this paper,and the basic physical properties of stable structures,including mechanical properties,electronic properties and optical properties are predicted from the microscopic point of view of atoms.The main research contents and results of this paper are as follows:1.Si-Ge alloys in P41212 and P-3m1 phase have been designed with the doping of homogeneous elements,and their crystal structure,stability and physical properties have been studied.The simulation of elastic constants and phonon spectra shows that the Si-Ge alloys in P41212 and P-3m1 phase are dynamic and mechanical stable.The SiGe alloys in P41212 phase are brittle materials with varying degrees of elastic anisotropy,while the elastic modulus of Si-Ge alloys in P-3m1 phase decreases with the increase of germanium component.The band gaps of Si-Ge alloys in P41212 phase are close to the wide gap band,between 1.81-1.88 e V,which means that they have excellent radiation resistance characteristics and have potential applications in the aerospace field.Direct band gap semiconductors have an advantage in light absorption.The alloys obtained by adding germanium into P-3m1 silicon not only maintain the good characteristics of direct and quasi-direct band gap,but also have smaller effective carrier mass and better visible light absorption capacity,which indicates that P-3m1 phase Si-Ge alloys has good application value in optoelectronic devices and microelectronics.2.Two kinds of direct band gap semiconductor Si C alloys(I-43 d and P2/m Si C)are proposed based on the direct band gap properties of Si C materials.The C,Si and Si C in the optimized I-43 d and P2/m phases have good mechanical and dynamic stability.These two novel Si C structures remain stable at 50 GPa and 800 K,and their endurance in extreme environments indicates the possibility of synthesis under high temperature and pressure.The direct band gaps of I-43 d and P2/m Si C are 1.44 e V and0.99 e V,respectively.Compared with other Si C alloys,I-43 d and P2/m Si C have lower effective carrier mass,while suitable direct band gap and good transport properties mean that they have potential applications in microelectronic devices.Oxygen(O)and hydrogen(H)are often introduced as light element impurities in the process of synthesizing semiconductor materials.Therefore,the band structur Se of two novel Si C structures doped with O and H atoms has been investigated.It was found that the energy band structure of I-43 d Si C doped with H atom and P2/m Si C doped with O or H atom changed from direct band gap to metal property,indicating that their electronic properties are very sensitive to the doping of O and H atom.This is important to help researchers understand the underlying mechanism of regulating the electronic properties of Si C using doping methods.It is noteworthy that the excellent light absorption capacity and long absorption range enable I-43 d and P2/m Si C to be used in solar cells,infrared detection,atmospheric environment monitoring and many other fields.3.Based on the similarity of physical and chemical properties of homologous elements and carbon allotrope,this paper proposed Silicon allotrope with A4-A2B2,Z4-A3B1 structure and germanium allotrope with A4-A2B2,Z4-A3B1,Z-ACA,Z-CACB structure.The stability,mechanical properties,electronic properties and optical properties of carbon,silicon and germanium allotrope with five structures of A4-A2B2,Z,Z4-A3B1,Z-ACA,Z-CACB were studied.Among these allotropes,except Z-CACBSi(B/G=1.98,ν=0.283),the rest materials are all brittle.By comparing the Debye temperature of five kinds of carbon,silicon and germanium allotropes,it is confirmed that they have strong interatomic bonding force.The band structure prediction of five kinds of carbon,silicon and germanium allotropes reveals that Z-CACB-Si is a kind of semiconductor material with quasi-direct band gap,and A4-A2B2,Z-ACA-C,Z-CACBC and Z-CACB-Ge are direct band gap semiconductor materials.The ultra-wide band gaps of Z4-A3B1-C(5.57 e V)and Z-CACB-C(5.36 e V)have outstanding advantages in the application of next-generation optoelectronic devices.In addition,the optical absorption spectra in the visible region show that the optical absorption capacity of five silicon allotropes are greater than that of diamond silicon.The direct band gap characteristics and excellent photon absorption capability of Z4-A3B1-Si make it potentially useful in optoelectronic and microelectronic devices.