飛秒激光雙脈沖列誘導(dǎo)半導(dǎo)體表面自組裝周期結(jié)構(gòu)及其特性研究
發(fā)布時(shí)間：2018-12-25 08:47
【摘要】：飛秒激光在材料表面誘導(dǎo)自組裝周期結(jié)構(gòu)(LIPSS)一直是光學(xué)領(lǐng)域研究的重點(diǎn)。近幾十年來,科研人員主要關(guān)注兩個(gè)方面:一個(gè)是自組裝周期結(jié)構(gòu)的形成機(jī)理;另一個(gè)是拓展其應(yīng)用領(lǐng)域。研究表明飛秒激光輻照材料表面激發(fā)的電子密度水平對(duì)周期結(jié)構(gòu)的誘導(dǎo)有著重要影響。飛秒激光的超短脈寬比燒蝕過程中涉及到的物理化學(xué)過程的時(shí)間尺度短或者與其相當(dāng)。因此,采用飛秒激光雙脈沖列輻照技術(shù)可為操控瞬態(tài)局域電子動(dòng)力學(xué)過程、調(diào)控瞬態(tài)局域材料特性、控制相應(yīng)的相變機(jī)理提供很多的可能性,也為探索LIPSS的形成機(jī)理提供了的新的視角。本文采用不同偏振的飛秒激光雙脈沖列,在不同延遲時(shí)間下輻照ZnO和6H-SiC表面,得到了不同形貌的納米形貌。主要通過改變雙脈沖序列間的延遲時(shí)間,調(diào)節(jié)材料表面被激發(fā)的電子密度水平,從而控制材料表面被誘導(dǎo)的周期結(jié)構(gòu)以及結(jié)構(gòu)特性。本文的主要內(nèi)容包括:1、通過采用可調(diào)節(jié)延遲時(shí)間的飛秒激光雙脈沖序列輻照ZnO表面,得到了低空間頻率周期條紋結(jié)構(gòu)(LSFL)和高空間頻率周期條紋結(jié)構(gòu)(HSFL);發(fā)現(xiàn)隨著延遲時(shí)間的增加,LSFL逐漸向HSFL轉(zhuǎn)變。使用電子速率方程分別計(jì)算不同延遲時(shí)間下由800nm和400nm的飛秒激光輻照ZnO表面所激發(fā)的電子密度。依據(jù)電子密度計(jì)算結(jié)果,結(jié)合Sipe理論,解釋了結(jié)構(gòu)轉(zhuǎn)變現(xiàn)象。2、通過可調(diào)節(jié)延遲時(shí)間的交叉偏振飛秒激光雙脈沖序列輻照ZnO表面,得到了不同形貌的納米結(jié)構(gòu);對(duì)ZnO表面進(jìn)行磁控濺射噴金和退火處理,成功制備出具有表面拉曼散射增強(qiáng)的基底。在給定的激光參數(shù)下,該基底的拉曼增強(qiáng)因子最高達(dá)到1.2×104。3、通過采用可調(diào)節(jié)延遲的共線雙脈沖序列輻照6H-SiC表面,得到了LSFL和HSFL兩種周期結(jié)構(gòu)。同樣發(fā)現(xiàn)隨著延遲時(shí)間的增加,LSFL逐漸向HSFL轉(zhuǎn)變,對(duì)此現(xiàn)象進(jìn)行了理論分析。更特別的是,在6H-SiC表面燒蝕區(qū)觀察到了雙折射現(xiàn)象,且雙折射現(xiàn)象會(huì)隨著延遲時(shí)間的改變而變化,我們對(duì)造成上述現(xiàn)象的因素,進(jìn)行了系統(tǒng)的分析。
[Abstract]:Femtosecond laser induced self-assembly periodic structure (LIPSS) on the surface of materials has been the focus of optical research. In recent decades, researchers have focused on two aspects: one is the formation mechanism of self-assembled periodic structure, the other is to expand its application field. The results show that the electron density level induced by femtosecond laser irradiation plays an important role in the induction of periodic structures. The ultrashort pulse width of femtosecond laser is shorter than or equivalent to the time scale of the physical and chemical processes involved in the ablation process. Therefore, the technology of femtosecond laser double pulse train irradiation can provide many possibilities for manipulating transient local electron dynamics, regulating transient local material characteristics, and controlling the corresponding phase transition mechanism. It also provides a new perspective for exploring the formation mechanism of LIPSS. In this paper, ZnO and 6H-SiC surfaces were irradiated with femtosecond laser double pulses with different polarization at different delay time, and different morphologies were obtained. By changing the delay time between the two pulse sequences and adjusting the level of electron density excited on the surface of the material, the induced periodic structure and structural characteristics of the material surface are controlled. The main contents of this paper are as follows: 1. By using femtosecond laser double pulse sequence with adjustable delay time to irradiate the surface of ZnO, the low spatial frequency periodic fringe structure (LSFL) and the high spatial frequency periodic stripe structure (HSFL); are obtained. It was found that with the increase of delay time, LSFL gradually changed to HSFL. The electron density excited by 800nm and 400nm femtosecond laser irradiation on the surface of ZnO was calculated by using the electron rate equation. According to the results of electron density calculation and Sipe theory, the phenomenon of structure transition is explained. 2. Different morphologies of nanostructures are obtained by cross-polarization femtosecond laser double pulse sequence with adjustable delay time to irradiate the surface of ZnO. The substrate with enhanced surface Raman scattering was successfully prepared by magnetron sputtering and annealing on the surface of ZnO. Under the given laser parameters, the maximum Raman enhancement factor of the substrate is 1.2 脳 104.3. Two periodic structures of LSFL and HSFL have been obtained by irradiating the surface of 6H-SiC with a collinear dual-pulse sequence with adjustable delay. It is also found that with the increase of delay time, LSFL gradually changes to HSFL, and this phenomenon is analyzed theoretically. In particular, birefringence is observed in the ablation region of 6H-SiC surface, and the birefringence changes with the change of delay time.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN249;TN304
本文編號(hào)：2390954
[Abstract]:Femtosecond laser induced self-assembly periodic structure (LIPSS) on the surface of materials has been the focus of optical research. In recent decades, researchers have focused on two aspects: one is the formation mechanism of self-assembled periodic structure, the other is to expand its application field. The results show that the electron density level induced by femtosecond laser irradiation plays an important role in the induction of periodic structures. The ultrashort pulse width of femtosecond laser is shorter than or equivalent to the time scale of the physical and chemical processes involved in the ablation process. Therefore, the technology of femtosecond laser double pulse train irradiation can provide many possibilities for manipulating transient local electron dynamics, regulating transient local material characteristics, and controlling the corresponding phase transition mechanism. It also provides a new perspective for exploring the formation mechanism of LIPSS. In this paper, ZnO and 6H-SiC surfaces were irradiated with femtosecond laser double pulses with different polarization at different delay time, and different morphologies were obtained. By changing the delay time between the two pulse sequences and adjusting the level of electron density excited on the surface of the material, the induced periodic structure and structural characteristics of the material surface are controlled. The main contents of this paper are as follows: 1. By using femtosecond laser double pulse sequence with adjustable delay time to irradiate the surface of ZnO, the low spatial frequency periodic fringe structure (LSFL) and the high spatial frequency periodic stripe structure (HSFL); are obtained. It was found that with the increase of delay time, LSFL gradually changed to HSFL. The electron density excited by 800nm and 400nm femtosecond laser irradiation on the surface of ZnO was calculated by using the electron rate equation. According to the results of electron density calculation and Sipe theory, the phenomenon of structure transition is explained. 2. Different morphologies of nanostructures are obtained by cross-polarization femtosecond laser double pulse sequence with adjustable delay time to irradiate the surface of ZnO. The substrate with enhanced surface Raman scattering was successfully prepared by magnetron sputtering and annealing on the surface of ZnO. Under the given laser parameters, the maximum Raman enhancement factor of the substrate is 1.2 脳 104.3. Two periodic structures of LSFL and HSFL have been obtained by irradiating the surface of 6H-SiC with a collinear dual-pulse sequence with adjustable delay. It is also found that with the increase of delay time, LSFL gradually changes to HSFL, and this phenomenon is analyzed theoretically. In particular, birefringence is observed in the ablation region of 6H-SiC surface, and the birefringence changes with the change of delay time.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN249;TN304
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