| In recent years,more and more research focused on the color centers in wide band gap(WBG)materials such as diamond used in quantum technology.Point defects in diamond have coherent optical transitions,Zeeman energy levels,and isolated atomic hyperfine structures.The energy level of the diamond color center has a strong temperature dependence,and this temperature dependence has great potential in temperature sensing.At the same time,for the quantum control and ultra-sensitive detection of diamond,the interaction between the diamond device and the environment needs to be considered,and temperature is one of the important influencing factors.Moreover,as the excellent properties of diamond color centers are applied and developed in more and more scenarios,the preparation of high-quality color centers with long spin coherence time has become a research hotspot.Femtosecond laser direct writing preparation of WBG semiconductor color centers has technical advantages such as high color center preparation efficiency and no need for subsequent annealing,which provides a new idea for the preparation of high-quality color centers and the integration of color center devices.Based on this,this paper carried out the research on the temperature characteristics of diamond color center and the method of femtosecond laser preparation.The main contents and conclusions of this paper are as follows:First,with the background of the properties and applications of diamond color centers,the structure,classification and growth of diamonds are introduced.The specific application and application prospects of diamond color centers are introduced in detail,and the main processing methods of diamond color centers are introduced.The mechanism of femtosecond laser processing is studied,the dynamic equation and two temperature model of the interaction between femtosecond laser and semiconductor are introduced,and the main parameters affecting the femtosecond laser processing process are analyzed.At the same time,the principle of photoluminescence(PL)was introduced,providing a theory for subsequent characterization work.Secondly,based on the variable temperature characterization by confocal fluorescence spectrometer,the temperature characteristics of the diamond color center are explored.PL spectroscopy was used to study the optical properties of defects in Ib diamond prepared by CVD and HPHT at a temperature of 77-297K.The temperature dependence of 2.65 e V center,NV~0,NV~-,Si V~-,3H was explored respectively.Theoretical models of the temperature dependence of the(Zero phonon line,ZPL)of diamond color center is established.Then,the experiment of femtosecond laser machining diamond color center is carried out,and the key parameters such as machining energy and pulse number are studied.Combined with the sample cleaning process,the preparation of diamond color center is realized.Finally,the morphology after fs laser processing is analyzed.In the single-pulse processing area,the change of the ablation pit diameter with pulse energy is discussed.The surface processed by different pulse numbers was characterized,and the cumulative effect under the action of multiple pulses was introduced.Combined with Raman spectroscopy,the phase transition of the processing area is introduced in detail,and the transverse and longitudinal damages of the processing area are characterized by Raman imaging.Through low-temperature PL spectroscopy,the generation of color centers in the processing area was characterized,and interstitial-type and vacancy-type defects generated in the processing area were found,and the ZPL of the NV color center was directly observed in the processing area.On this basis,the low-temperature PL imaging characterization of the color center spatial distribution in the processing area was carried out,and a theoretical explanation was put forward for the formation process of the color center under the high-throughput processing of the long-pulse femtosecond laser. |
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