【作者】 许丽；

【导师】 黄伟其；

【作者基本信息】 贵州大学 ， 理论物理， 2008， 硕士

【摘要】 将功率为30W、波长为1064nm、脉宽8ns、重复频率800HZ的YAG激光束照射在电阻率为10—20Ωcm的P型掺杂单晶硅样品表面打出小孔,在孔内的侧壁上形成较规则的网孔状结构,该结构有很强的光致荧光(PL),发光峰中心约在706nm处。该结构的光致荧光峰强度比电化学加工纳米硅的光致荧光峰大约大两个数量级以上。通过改变激光辐照的时间和功率使到达硅表面的激光能量改变,发现网孔状结构的尺寸发生变化,同时光致荧光的强度也发生改变,但光致荧光峰的位置不变。这种光致荧光峰的钉扎效应单独用量子受限效应不能很好地解释。我们发现:当激光辐照时间约为9s时,孔洞侧壁上的网孔状结构较稳定、且有较强的PL发光。我们将激光与硅样品的作用隔离于无氧化的环境里,分别比较了将硅样品浸入酒精、氢氟酸和水中进行激光加工与检测的结果。发现在酒精和氢氟酸中激光加工的硅样品几乎不发光;而在水中的激光加工的样品有微弱的PL发光,水在激光的辐照下会发生分解、释放出少量的氧原子。这证实了氧在光致荧光增强效应方面起着重要的作用。我们用冷等离子体波模型来解释孔侧壁网孔状结构形成的机理;并用量子受限及其硅纳晶与氧化硅界面态的综合模型来解释纳米网孔结构的PL发光的钉扎与增强效应。更多还原

【Abstract】 A kind of hole-net structure can be formed on silicon sample by irradiation with pulse laser of power 30W、wavelength 1064nm、repeat frequency 800HZ and pulse width 8ns. The photoluminescence （PL） emission is enhanced in the hole-net structure. The PL peak center is about 706nm. The optimum conditions are obtained in preparing （irradiation time and laser power）. We have found that the PL peak center do not alter with changing sizes of hole-net structure. Pinning effect of PL emission is not interpreted by quantum confinement alone. Under the optimum conditions in preparing process, the sample with an enhanced PL emission and more stable low-dimensional structures can be obtained by 9s irradiationA series of experiments have been designed to detect the affection of the oxidation on the hole-net structure of silicon to PL emission. In the preparing and detecting process, the sample irradiated was immersed in HF、ethanol, and pure water, respectively. it is found that there is no PL emission almost on the earlier oxygen-free samples in HF and ethanol; It is found that there is weak PL emission on samples in pure water because pure water under laser irradiation releases oxygen. It is confirmed that the oxygen plays an important role in PL emission of sample. The enhancing effect of the PL emission is not interpreted by the model of the quantum confinement and luminescence center. So a model for explaining the effect was proposed in which the trap states of the interface between SiO₂ and low-dimensional nanocrystal play an important role. The plasma wave model is used to explain the mechanism forming hole-net structure.更多还原