一、一步合成法合成具有形狀控制的小顆硫化鉛奈米晶體與他們的生長機制 二、一步合成法合成大顆且具有明確晶面的硫化鉛奈米粒子與其晶面導向的導電性量測

I. One Step Synthesis of Small PbS Nanocrystals with Shape Control and Their Growth Mechanism II. One Step Synthesis of Large PbS Nanocrystals with Well-Defined Facets and Their Facet-Dependent Electrical Conductivity Measurements

陳祥生(Chen, Hsiang Sheng)

指導教授 ： 黃暄益

國立清華大學/理學院/化學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00103

摘要

我們在水相中以一步合成法成功合成出小顆硫化鉛奈米粒子，所合成出的正方體的邊長為21奈米、正八面體邊長為57奈米，並深入探討其成核與晶體成長的機制，借由了解這些機制我們可以掌握控制其大小及形貌的關鍵因素，也因此我們得以以較簡單的方式大量生產這些極小顆且具有均一形狀的硫化鉛奈米粒子；此外，我們也因此得以製造出較大顆的硫化鉛多面體使得單顆硫化鉛粒子的導電性量測得以被實現。
先前我們已觀測到氧化亞銅晶面導向的導電性，而在本實驗中我們又再次借由量測面凸正方體、截角截邊正方體、正八面體與截角截邊正八面體硫化鉛粒子的I-V曲線來展示硫化鉛粒子的晶面導向導電性，其中我們發現{111}晶面幾乎不導電，{100}與{110}導電性相較之下極好，又以{110}最好，與{111}晶面差了約二至三個數量級。這也證實了晶面導向導電性是廣泛存在於半導體之中的，我們認為這些導電性的差異來自于半導體界面上不同晶面所造成的能帶扭曲幅度不同。

關鍵字

硫化鉛 ； 晶面 ； 導電性 ； 奈米晶體

並列摘要

We have fabricated small PbS nanocrystals (cubes: 21 nm; octahedra: 57 nm) in aqueous solution using an one-step approach. We gain knowledge in manipulating their shape and size by clear exploration of the relation between nucleation and crystal growth. This enables us to scale up the production using a more intuitive method. Also, the refined seeding growth method allows us to enlarge the size of PbS polyhedra, fulfilling single particle electrical conductivity measurements.
Facet-dependent electrical conductivity of Cu2O crystals has been previously revealed. In this study, we have again successfully demonstrated the facet-dependent electrical property of PbS using face-raised cubes, edge-and corner-truncated cubes, edge- and corner-truncated octahedra and pristine octahedra with the size of several hundreds of nanometers. Two tungsten probes are manipulated to contact the opposite faces of a single particle. The {110} facets showed the highest electrical conductivity, followed by the {100} facets and the {111} facets were observed to be the least conductive. The {111} facets are 500 times less conductive than the {110} faces at an applied voltage of 5 V. This study suggests that facet-dependent electrical conductivity should be regarded as an intrinsic property for semiconductors.

並列關鍵字

Lead Sulfide ； Facet ； Conductivity ； Nanocrystal

參考文獻

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