| The ultra-wide band gap semiconductor materialβ-Ga2O3 has good thermal and chemical stability,high transmittance in the visible and ultraviolet region,and is suitable for large-scale production,soβ-Ga2O3 has become a strong competitor for the next generation of high-power electronic devices and deep ultraviolet sun-blind photodetectors.However,the low conductivity ofβ-Ga2O3 seriously restricts its further development in optoelectronics,and its performance can be improved by doping.In recent years,there are some research reports on transition metal Nb,Ti,Ta dopedβ-Ga2O3,but their research has some limitations and is not comprehensive,they need to be studied systematically.Interstitial H and O vacancies are difficult to avoid in the experimental process,and their effects on material properties can not be ignored.In this paper,using the CASTEP module in MS 8.0 software,the first-principle plane wave ultra-soft pseudopotential GGA+U method based on density functional theory is used to calculate the electronic structure and optoelectronic properties of oxygen vacancy and Nb,Ti,Ta,H-dopedβ-Ga2O3.Theβ-Ga2O3 supercell model（1×3×2）with 120 atoms was constructed,the doping position was changed to form a more stable system,and the effects of doping concentration（0.833 at%,1.667 at%and2.5 at%）on energy band,density of states,absorption spectrum,dielectric function,conductivity and mobility were calculated and analyzed.When the concentration is fixed,O vacancy and interstitial H are introduced to analyze the effects of O vacancy and interstitial H on the above properties.The results show thatβ-Ga2O3 doped with Nb,Ti and Ta can form n-type direct band gap semiconductors.When doped,Nb,Ti and Ta atoms tend to replace octahedral coordinated Ga atoms.Except for Ga47O72M1H1（M=Nb/Ti/Ta）system,all the other systems have lower formation energy,higher stability and easier formation under the condition of Ga-rich.With the increase of doping concentration,the lattice constant and volume also increase,the band gap of the system narrows gradually,and the deep ultraviolet detection ability is enhanced.At the same time,the increase of doping concentration accelerates the separation of holes and electrons,prolongs the carrier lifetime and improves the electrical conductivity of the system.O vacancy is a deep donor,which can not be used as an effective electron charge source,which reduces the electrical conductivity of the system,while interstitial H can improve the conductivity of the system.In the doping system of the three elements,the formation energy of Nb-dopedβ-Ga2O3 is the lowest,it is easier to form,and the electrical conductivity is better;the mobility of Ti-dopedβ-Ga2O3 is larger;Ta dopedβ-Ga2O3 has the highest light absorption intensity,stronger UV detection ability and better carrier activity.These conclusions provide a theoretical basis for the wide application of dopedβ-Ga2O3materials and are beneficial to the design and fabrication of newβ-Ga2O3 devices. |
