Photoluminescence Studies Of ?a Diamond After Near Threshold Energy Irradiation

Diamond as the fourth generation semiconductor material,it is widely used in quantum computer,5G communication,semiconductor lighting and other fields because of its excellent performance.For semiconductors,it is difficult to control the generation of defects during the crystal growth process.In general,irradiation and annealing are traditional methods to control the macro performance of semiconductor devices.However,MeV high-energy electron irradiation would cause multi-level collisions of carbon atoms in diamond and produce complex defects.In contrast,the near threshold energy electron irradiation can introduce simple and isolated point defects,which is conducive to the study of diamond defects.In this paper,the ?a diamond synthesized by microwave plasma chemical vapor deposition(MPCVD)is used as the research object,and the irradiation defects are introduced into the crystal by 200 keV(near threshold energy)electron irradiation.The low-temperature photoluminescence(PL)spectroscopy is employed to characterize the defects.The temperature dependence,power dependence,distribution along the depth of the zero phonon lines(ZPLs)are studied.In addition,the effect of annealing on the ZPLs distribution is also explored.The structures of defects are clarified by combined with the above analysis.The main results are presented as follows: There are 1.673 eV(GR1 center),2.091 eV and 2.253 eV ZPLs in the spectrum of ?a diamond by 200 keV near threshold energy electron irradiated,the 1.673 eV zero phonon line is caused by a single neutral vacancy defect,which is recorded as GR1 center.With the increase of laser power,the ZPLs of 2.091 eV and 2.253 eV enhanced with the increase of GR1 center,there is a linear relationship between them;With the increase of measurement temperature,the peak position of the zero phonon line shifts red,the intensity decreases and the full width at half-maximum(FWHM)broadens.The ZPLs at 2.091 eV and 2.253 eV in ?a diamond presented a small peak shift of defects,the thermal softening coefficient is lower than that of ideal diamond;In addition,the values of Huang-Rhys factor and longitudinal optical phonon energy at 2.091 eV and 2.253 eV ZPLs are lower than those of GR1 center.The results show that the lattice relaxation energy of 2.091 eV and 2.253 eV ZPLs is small,the electron-phonon coupling strength is weak,and the lattice deformation is small during the electron transition;With the increase of crystal depth,the increase coefficient of NV center intensity is near to the difference between the attenuation coefficients of GR1 center and 2.091 eV ZPL.Therefore,it is speculated that 2.091 eV defects fill the vacancy in NV center,resulting in the rapid attenuation of 2.091 eV ZPL.During the annealing process,the ZPLs of 2.091 eV?2.253 eV and GR1 centers show different annealing characteristics.In summary,the ZPLs at 2.091 eV and 2.253 eV are caused by intrinsic carbon interstitial atomic defects.