Effects of coexistent pores and paramagnetic defects on positron annihilation in silicon oxide thin films
Effects of coexistent pores and paramagnetic defects on positron annihilation in silicon oxide thin films
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DOI：
10.1063/1.1555698
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发表时间：
2003-03
影响因子：
3.2
通讯作者：
R. Yu;K. Ito;K. Hirata;W. Zheng;Y. Kobayashi
中科院分区：
文献类型：
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作者：
R. Yu;K. Ito;K. Hirata;W. Zheng;Y. Kobayashi
在不同氩压下，采用射频溅射法制备不同孔隙率的SiOx （1.5<x<2）薄膜，测量了正电子2γ湮灭的多普勒展宽和正电子3γ湮灭（I3γ）的概率。随着Ar压力的增加，I3γ的增加是由于薄膜的开孔率增加。在顺磁缺陷浓度恒定的条件下，多普勒展宽S参数随着I3γ的增加和薄膜开孔率的增加而增大。这是由于p-Ps对511 kev2γ湮灭峰的相对贡献增强，这是由于o-Ps的拾取湮灭概率降低的结果。S参数与I3γ之间的关系受到顺磁缺陷的强烈影响，这意味着具有较高开孔率的膜不一定具有较高的S参数。具有高浓度铅中心的低孔隙率薄膜表现出…
We measured the Doppler broadening of positron 2γ annihilation and the probability of positron 3γ annihilation (I3γ) for paramagnetic defects (E′ and Pb) containing SiOx (1.5<x<2) films with different porosities, which were prepared by radio-frequency cosputtering of Si and SiO2 at different Ar pressures. The observed increase of I3γ with increasing Ar pressure was attributed to the increased open porosity of the film. Under a condition of constant paramagnetic defect concentration, Doppler broadening S parameter increases with increasing I3γ and open porosity of the film. This was caused by enhancement of a relative contribution from p-Ps to the 511 keV 2γ annihilation peak as a result of reduced probability of o-Ps pickoff annihilation. The relationship between the S parameter and I3γ can be affected strongly by the paramagnetic defects in the sense that film with a higher open porosity does not necessarily present a higher S parameter. A low porosity film with higher concentration Pb centers exhibited ...