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Resonant Tunnelling and Storage of Electrons in Si Nanocrystals within a-SiNx/nc-Si/a-SiNx Structures
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The a-SiNx/nanocrystalline silicon (nc-Si)/a-SiNx sandwiched structures with asymmetric double-barrier are fabricated in a plasma enhanced chemical vapour deposition (PECVD) system on p-type Si substrates. The nc-Si layer in thickness 5nm is fabricated from a hydrogen-diluted silane gas by the layer-by-layer deposition technique. The thicknesses of tunnel and control SiNx layers are 3nm and 20nm, respectively. Frequency-dependent capacitance spectroscopy is used to study the electron tunnelling and the storage in the sandwiched structures. Distinct frequency-dependent capacitance peaks due to electrons tunnelling into the nc-Si dots and capacitance-voltage (C - V) hysteresis characteristic due to electrons storage in the nc-Si dots are observed with the same sample. Moreover, conductance peaks have also been observed at the same voltage region by conductance-voltage (G - V) measurements. The experimental results demonstrate that electrons can be loaded onto nc-Si dots via resonant tunnelling and can be stored in our a-SiNx/nc-Si/a-SiNx structures. 相似文献
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分散固相萃取结合高效液相色谱-串联质谱法测定羊肝中19种全氟烷基酸 总被引:1,自引:0,他引:1
建立了羊肝样品中19种全氟烷基酸(PFAs)的高效液相色谱-串联质谱检测方法。样品经酸化乙腈提取,加入乙二胺-N-丙基硅烷(PSA)、C18、石墨化炭黑(GCB)3种吸附剂后涡旋振荡对样品进行净化。以高效液相色谱-串联质谱(HPLC-MS/MS)检测萃取液中PFAs含量,采用C18色谱柱分离,负离子模式电喷雾电离,配合多级反应离子扫描(MRM)定性分析目标化合物。考察了盐酸和吸附剂的用量对加标回收率的影响,优化了主要影响因素和实验条件。在优化条件下采用同位素标记内标物进行定量分析。19种PFAs在0.05~20 μg/kg范围内线性关系良好,相关系数R>0.998,检出限(LOD)为0.004~0.111 μg/kg,定量限(LOQ)为0.012~0.370 μg/kg。在0.5、1.0、2.0 μg/kg加标水平下,19种PFAs的加标回收率为80%~128%,相对标准偏差(RSD)范围为0.31%~11.1%。该方法快速、简单、准确,适用于羊肝样品中19种PFAs的检测分析。 相似文献
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本文所介绍的洗衣机用电子定时控制器与本刊1982年第九期所发表的有所不同,其特点是电路简单,所用元器件较少.其电路图如图1所示;工作原理可分成三个部分,现分别简述如下. 相似文献
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