Calculation Study On The Microstructure And Carrier Capture Sections Of Sulfur Impurities In Silicon

Defects play an important role in tuning the performance of optoelectronic devices,but at the same time nonradiative carrier capture induced by defects is also a key factor limiting their performance.The carrier capture cross section can be measured experimentally by means of DLTS,etc.,however,it is difficult to study the cross section using first-principles calculations.In recent years,the method of calculating the carrier capture cross section based on the electron-phonon coupling effect and static coupling theory has been applied to systems such as Ga N,but little research has been reported for the Si system.In this paper,we focus on the microstructure and carrier capture cross sections of S impurity in Si.The key step to calculate the capture cross section is to calculate the electron-phonon coupling matrix elements,but the original module for calculating the electron-phonon coupling matrix elements in Quantum Espresso cannot take into account the spin polarization case.Therefore,we implanted the spin polarization part into this calculation module and performed benchmark tests with Ga N and Cu₂Zn Sn S₄ systems to demonstrate the accuracy of the procedure.We systematically investigated the defect configuration,defect energy level,and corresponding carrier capture cross section of S_Si substitution defect in the S-doped Si system.We find that S⁺_Si has a higher distorted configuration besides a high symmetry configuration.The calculations reveal that the defect deep energy level corresponding to these two configurations are close and consistent with the experimental observations;the hole-capture cross section of S⁺_Si based on the distorted configuration is consistent with the experiment,proving that the hole capture of S⁺_Si is a multi-phonon process;while the hole-capture cross section of S⁰_Si is significantly lower than the experimental data,indicating that the hole capture of S⁰_Si is not a multi-phonon process,but an Auger process analyzed experimentally.The results of this paper provide a practical calculation method for predicting carrier capture cross sections in optoelectronic materials based on the electron-phonon coupling effect and static coupling theory.