本文選題：薄膜晶體管 + 雙有源層　； 參考：《江南大學(xué)》2017年碩士論文

【摘要】：現(xiàn)如今平板顯示技術(shù)正在急速發(fā)展,而薄膜晶體管(thin film transistor,TFT)作為其核心組成器件更是受到眾多研究者的關(guān)注。在此前非晶硅TFT、多晶硅TFT作為像素開關(guān)得到廣泛應(yīng)用,但是自從穩(wěn)定性好、低溫制備性能良好、均勻性好、透光率高的非晶銦鎵鋅氧化物薄膜晶體管(a-IGZO TFT)被研制出來之后,便迅速占領(lǐng)市場。然而隨著技術(shù)的發(fā)展,視頻格式的變化對設(shè)備的分辨率、清晰度的要求日益增高,現(xiàn)如今的設(shè)備已經(jīng)滿足不了廣大用戶的強烈需求,便不斷地有雙層有源層TFT被研究出來。2005年,美國的Dehuff研究小組研制出非晶銦鋅氧化物薄膜晶體管(a-IZO TFT),其遷移率高、開態(tài)電流高、低溫制備性能也較好,其缺點便是穩(wěn)定性不高。因此本文在此基礎(chǔ)上,對TFT器件采用雙層有源層結(jié)構(gòu),前溝道為a-IZO材料,利用a-IZO的高遷移率的特性提高TFT器件的開態(tài)電流;背溝道為a-IGZO材料,利用a-IGZO的低關(guān)態(tài)電流的特性提高TFT器件的開關(guān)電流比。本文的研究重點如下:1)本文對雙有源層TFT器件的兩種有源層材料的厚度組成進(jìn)行研究,即設(shè)定雙層有源層TFT的有源層的總厚度為一定值,改變前溝道為a-IZO材料、背溝道為a-IGZO材料的厚度比,根據(jù)其厚度比的變化,研究其雙有源層TFT的導(dǎo)電機制,以及有源層的載流子濃度的變化對TFT器件的電學(xué)特性的影響。并且對比討論這兩種材料的厚度在怎樣的狀態(tài)下才能使TFT的器件性能達(dá)到最佳。研究得出,當(dāng)雙層有源層TFT器件的前溝道材料a-IZO的厚度為5nm(a-IZO與a-IGZO的厚度比為5/35)時,TFT器件的開關(guān)電流比達(dá)到最大值、閾值電壓最為接近0、亞閾值擺幅也為所研究的所有厚度比例TFT中的最小值、其穩(wěn)定穩(wěn)定性也佳。并且研究過程中發(fā)現(xiàn),雙層有源層TFT的電學(xué)特性普遍比單層有源層TFT的特性要好。2)態(tài)密度模型(density of states,DOS)是a-IGZO半導(dǎo)體與a-IZO半導(dǎo)體的電學(xué)特性的一個重要表征,在眾多研究者對其特性的模擬研究中,均對DOS模型中的參數(shù)進(jìn)行了研究。由于a-IZO較a-IGZO半導(dǎo)體相比,只是缺少了Ga元素,因此本文便結(jié)合現(xiàn)有的a-IGZO DOS模型對兩種有源層材料的態(tài)密度模型參數(shù)進(jìn)行研究。主要討論其特定參數(shù)的變化對TFT器件的影響程度。仿真結(jié)果表明:a)前溝道a-IZO的導(dǎo)帶尾態(tài)在E=EC時的nta濃度的增加,會導(dǎo)致雙有源層TFT器件的開態(tài)電流的減小、閾值電壓的增加;前溝道a-IZO的導(dǎo)帶尾態(tài)的特性斜率wta的增加,會導(dǎo)致導(dǎo)帶尾態(tài)的面積增加以及TFT器件的開態(tài)電流的減小、閾值電壓的增加、亞閾值擺幅的減小。b)背溝道材料a-IGZO材料的氧空位態(tài)的變化對TFT器件的特性影響巨大,并且氧空位態(tài)與費米能級的相對位置對TFT器件也會有影響。因此前溝道的導(dǎo)帶尾態(tài)(即陽離子的空軌道)對TFT器件的整體影響巨大,而背溝道的缺陷態(tài)對TFT器件的影響更加不可忽略。
[Abstract]:Now flat display technology is developing rapidly, and thin film transistor (TFT), as its core component, is paid more and more attention by many researchers. Before the amorphous silicon TFT, polycrystalline silicon TFT is widely used as a pixel switch, but since the stability is good, the low temperature preparation performance is good, the uniformity is good, the transmittance is good. After the high amorphous indium and gallium oxide thin film transistor (a-IGZO TFT) has been developed, the market is rapidly occupied. However, with the development of technology, the changes in video format have increased the resolution and clarity of the equipment. Nowadays, the equipment has been unable to meet the strong needs of the broad users, and there is a double layer of active layer TF. T has been studied for.2005 years. The Dehuff research team in the United States developed amorphous indium oxide thin film transistor (a-IZO TFT), which has high mobility, high open state current and good low temperature preparation performance. The disadvantage is that the stability is not high. Therefore, on this basis, the TFT device uses a double layer active layer structure, the front channel is a a-IZO material and a is used. The high mobility of -IZO improves the open state current of the TFT device; the back channel is a a-IGZO material, and the switching current ratio of the TFT device is improved by the characteristics of the low off state current of the a-IGZO. The focus of this paper is as follows: 1) this paper studies the thickness composition of the two active layer materials of the double active layer, that is, setting the double layer active layer TFT The total thickness of the active layer is a certain value, and the thickness ratio of the front channel is a-IZO material and the back channel is the thickness ratio of the a-IGZO material. According to the change of the thickness ratio, the conductive mechanism of the double active layer TFT and the influence of the carrier concentration of the active layer on the electrical characteristics of the TFT device are studied. And the thickness of the two materials is compared and discussed. It is concluded that when the thickness of the front channel material a-IZO of the double active layer TFT device is 5nm (a-IZO and a-IGZO thickness ratio 5/35), the switching current ratio of the TFT device is maximum, the threshold voltage is closest to 0, and the sub threshold swing is also in all the thickness proportion TFT studied. In the course of the study, it is found that the electrical properties of the double layer active layer TFT are generally better than that of the single layer active layer TFT (.2). The density of states (DOS) is a important characterization of the electrical properties of a-IGZO semiconductors and a-IZO semiconductors, and in the simulation of the characteristics of a large number of researchers. All the parameters in the DOS model are studied. As compared with the a-IGZO semiconductor, a-IZO is only missing the Ga element, so this paper combines the existing a-IGZO DOS model to study the parameters of the density model of the two active layer materials. The main discussion is about the influence of the change of the specific parameters on the TFT device. The simulation results show that: before a) The increase of the NTA concentration of the tail state of the channel a-IZO leads to the increase of the NTA concentration at E=EC, which will lead to the decrease of open state current and the increase of the threshold voltage. The increase of the characteristic slope WTA of the tail state of the front channel a-IZO leads to the increase in the area of the tail state of the guide band and the decrease of the open state current of the TFT device, the increase of the threshold voltage and the subthreshold value. The decrease of the swing.B) the change of oxygen vacancy in the a-IGZO material of the back channel material has great influence on the characteristics of the TFT device, and the relative position of the oxygen vacancy state and the Fermi level will also affect the TFT device. Therefore, the guide band tail state of the front channel (the cation empty orbit) has a great influence on the TFT device, and the defect state of the back channel is TFT The effect of the device can not be ignored.

【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN321.5

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本文編號：1877929