【作者】 刘铁驹；

【导师】 李养贤；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2004， 硕士

【摘要】 本文对直拉硅样品进行了不同剂量的快中子辐照，在硅中引入大量的亚稳态缺陷，研究这些亚稳态缺陷的形成，并在较宽的温度范围内对辐照样品进行了退火处理，研究退火后亚稳态缺陷的转化及同硅中氧的相互作用，应用傅立叶变换红外光谱技术（FTIR）、正电子湮没技术（PAT）和扫描电镜（SEM）进行了测试。 实验结果表明，快中子辐照在硅品格内引入了大量的辐照缺陷，这些缺陷作为正电子的俘获中心使得正电子湮没平均寿命升高，当辐照剂量高于1×10¹⁸ n.cm^-2，正电子湮没平均寿命不再升高。另外，快中子辐照对于直拉硅的间隙氧含量有很大影响，间隙氧含量随着辐照剂量的增加而减少，这主要归于样品中产生了大量的（V-O）复合体。 在辐照硅中，实验发现了一个新的红外吸收峰，其波数为485cm^-1。该峰只与辐照有关，对应复杂辐照缺陷，400℃退火可以基本消除。同时快中子辐照后硅中产生V-O复合体等缺陷，在低于600℃、1小时的退火也难以消除，表明快中子辐照直拉硅中的氧相关缺陷更加复杂。正电子湮没技术测试证明，快中子辐照直拉硅中在大约600℃退火时产生的多空位缺陷具有较长正电子寿命，可以使正电子平均寿命增加，当样品的正电子平均寿命达到最大时（360ps），其间隙氧含量降到一个极小值(4×10¹⁷atoms/cm³)，这说明氧参与了这些缺陷的形成。 本文对快中子辐照直拉硅中的缺陷和氧的相互作用进行了研究，快中子辐照促进了直拉硅中的氧沉淀，与以往NTDCZSi研究结果相比，其促进作用更加明显。辐照缺陷在1100℃高温热处理下快速分解、复合，形成了大量的形核中心，从而促进了硅中氧的沉淀。不同气氛下快中子辐照直拉硅中缺陷形成的差异很大，1100℃的高温退火中，与氩气氛相比，氮气氛退火样品中出现了更多缺陷。更多还原

【Abstract】 In Czochralski silicon crystals (CZSi) through fast neutron irradiation, formation and conversion of defects were investigated using Fourier transform infrared spectroscopy (FTIR), Positron annihilation technology (PAT) and Scanning electron microscope(SEM).The results showed that fast neutron irradiation induced large quantity of metastable defects which can be the capture centers of positron, positron annihilation average lifetime of samples increased with increasing of irradiation dosage. Positron annihilation average lifetime of irradiation samples through dosage up to 1 × 1018 n.cm-2 tended to constant. Moreover, concentrations of interstitial oxygen in samples changed after fast neutron irradiation. The interstitial oxygen concentration of the samples decreased with increasing of irradiation dosage. This result can be explained in terms of higher generation rates of (V-O) complex.A new vibrational infrared absorption band at about 485cm-1 appeared commonly in spectra of Czochralski-grown and Float-zone-grown silicon irradiated with fast neutron. The new vibrational infrared absorption band was assigned to local vibrational modes related to the complicated complex of irradiation defects that did not contain oxygen atoms. The new vibrational infrared absorption band at about 485cm-1 was annealed at about 400 ℃. It was difficult to annealing V-O complex in fast neutron irradiated Si under 600 ℃ for 1h. After annealing at 600 ℃, because of formation of multi-vacancy-type defects that have long positron lifetime , positron annihilation average lifetime increased. When the average positron lifetime increased to maximum value(360ps), the interstitial oxygen concentration decreased to minimum value(4×1017atoms/cm3). This result suggested that oxygen was involved in the formation of multi-vacancy-type defects.Interact of fast-neutron irradiation defects and oxygen impurity in CZ-Silicon was investigated in this paper. The result suggested that oxygen precipitation formed at high temperature was promoted by fast-neutron irradiation obviously. Compared with NTDCZSi , fast neutron irradiation accelerated precipitation in CZSi much more. Irradiation defects decompounded and recombined with oxygen impurity and large quantity of nucleation centers were introduced in CZSi bulk during annealing at 1100℃. In Nitrogen atmosphere, more defects were induced in fast neutron irradiated CZSi than in Argon atmosphere.更多还原