Positron/positronium annihilation in low dimensional silicon materials
Positron/positronium annihilation in low dimensional silicon materials
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DOI：
10.1016/0169-4332(96)00091-8
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发表时间：
1996-08
影响因子：
6.7
通讯作者：
Y. Itoh;H. Murakami;A. Kinoshita
中科院分区：
文献类型：
--
作者：
Y. Itoh;H. Murakami;A. Kinoshita
用正电子和正电子湮没技术研究了晶体硅阳极氧化制备的多孔硅。由高阻晶片制成的多孔硅有三个寿命分量(约0.2、约0.5和约30 ns)，而由低阻晶片制成的多孔硅只有两个寿命分量(约0.2和约0.5 ns，分别增加到200K以上)。在氧气气氛中，正电子的寿命变短，多普勒展宽湮没辐射的半高宽减小。正电子/正电子状态受表面态和多孔硅纳米腔内气体吸附剂的影响。我们推测，在与位于孔表面附近的未配对电子相互作用的情况下，一部分正电子通过自旋转化为副正电子。
Positron and positronium annihilation investigations were applied to porous silicon made by anodization of crystal silicon. While three lifetime components (ca. 0.2, ca. 0.5 and ca. 30 ns) were found for porous silicon made from high resistivity wafer, only two components (ca. 0.2 and ca. 0.5 ns which increased above 200 K) were obtained for porous silicon made from low resistivity wafer. The lifetime of ortho-positronium becomes short, and the full width at half maximum of the Doppler-broadened annihilation-radiation decreases in oxygen atmosphere. Positron/positronium states are affected by surface states and by gas adsorbents in the nanoscale cavities of the porous silicon. We deduce that a fraction of the ortho-positronium is converted to para-positronium through spin conversion, under interaction with unpaired electrons located near pore surfaces.