本文選題：帶隙　切入點(diǎn)：第一性原理計(jì)算　出處：《華東師范大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：過(guò)去幾十年,半導(dǎo)體納米結(jié)構(gòu)的研究引起了廣泛關(guān)注,量子限域效應(yīng)使其具備不同于體材料的新穎物性,從而能滿足功能應(yīng)用的需要。雖然IVA族元素C、Si Ge等眾多體系的納米線、納米片、納米帶等納米結(jié)構(gòu)已經(jīng)有了一系列的研究,然而,其物性和器件性能目前仍然有諸多不足,尋找和研究新型半導(dǎo)體納米結(jié)構(gòu)仍然非常必要。因此,本文研究了兩種單元素窄禁帶半導(dǎo)體的納米結(jié)構(gòu),第一個(gè)是二維層狀結(jié)構(gòu)的單層和多層As結(jié)構(gòu)(砷烯),第二個(gè)是Te的納米線和納米帶結(jié)構(gòu)。首先,本文通過(guò)第一性原理計(jì)算研究了二維褶皺蜂窩層狀結(jié)構(gòu)的As能帶結(jié)構(gòu)隨層數(shù)、面內(nèi)應(yīng)變的變化規(guī)律,發(fā)現(xiàn)層數(shù)和面內(nèi)應(yīng)變會(huì)導(dǎo)致間接帶隙到直接帶隙的轉(zhuǎn)變,而這種轉(zhuǎn)變是由于間接和直接帶隙的帶邊態(tài)對(duì)量子限制效應(yīng)與應(yīng)變的響應(yīng)不同所導(dǎo)致,間接帶隙的價(jià)帶帶邊態(tài)來(lái)自于平行于層平面的As-As鍵,而直接帶隙的價(jià)帶帶邊態(tài)來(lái)自于垂直層平面的As-As鍵。其次,本文還通過(guò)第一性原理計(jì)算對(duì)Te納米結(jié)構(gòu)的表面性質(zhì)與光學(xué)性質(zhì)進(jìn)行了研究。通過(guò)對(duì)Te表面性質(zhì)的研究,發(fā)現(xiàn)不同密勒指數(shù)面的表面能均比IVA族元素C Si Ge的表面能低,并且通過(guò)低密勒指數(shù)面組合構(gòu)成的一維納米線結(jié)構(gòu)都具有明顯的帶隙且沒(méi)有引入任何表面電子態(tài)。通過(guò)對(duì)Te光學(xué)性質(zhì)研究,發(fā)現(xiàn)Te晶體吸收譜在0-3 eV范圍內(nèi)的吸收峰主要是由于最靠近禁帶的兩個(gè)能帶之間的電子直接躍遷所導(dǎo)致的；Te納米線與納米帶結(jié)構(gòu)的吸收峰隨著尺寸的減小而逐漸藍(lán)移,帶隙隨著尺寸的減小而顯著增大。
[Abstract]:In the past few decades, the study of semiconductor nanostructures has attracted wide attention. Quantum limiting effect makes it have novel physical properties different from bulk materials, which can meet the needs of functional applications. There have been a series of studies on nanostructures such as nanochips and nanobelts. However, their physical properties and device properties still have many shortcomings, so it is still necessary to find and study new semiconductor nanostructures. In this paper, two kinds of nanocrystalline structures of narrow band gap semiconductor with single element are studied. The first is the single layer and multilayer as structure of two-dimensional layered structure, the second is the nanowire and nanoband structure of Te. In this paper, the variation of as energy band structure with the number of layers and the in-plane strain of two-dimensional folded honeycomb layered structure is studied by first principle calculation. It is found that the number of layers and in-plane strain will lead to the transition from indirect band gap to direct band gap. This transition is due to the different responses of the indirect and direct band edge states to the quantum confinement effect and the strain. The valence band edge states of the indirect band gaps are derived from the As-As bonds parallel to the layer plane. The valence band edge states of the direct band gap are derived from the As-As bond in the vertical plane. Secondly, the surface and optical properties of Te nanostructures are studied by first principle calculation. It is found that the surface energy of different Miller exponent surfaces is lower than that of IVA group element C Si GE. Moreover, the structure of one dimensional nanowire formed by the combination of low Miller exponent surface has obvious band gap and no surface electronic state is introduced. The optical properties of Te are studied. It is found that the absorption peak of Te crystal in the range of 0-3 EV is mainly due to the direct electron transition between the two energy bands closest to the band gap, which results in the blue shift of the absorption peaks of the nanowires and nanobelts with the decrease of the size. The band gap increases with the decrease of size.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN304;TB383.1

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本文編號(hào)：1645817