本文選題：ZnO　切入點(diǎn)：薄膜晶體管　出處：《北京交通大學(xué)》2016年博士論文

【摘要】：ZnO基TFT因其在平板顯示和透明電路領(lǐng)域的廣闊應(yīng)用前景而備受國(guó)內(nèi)外的關(guān)注。由于ZnO中存在Zn填隙、O空位等本征缺陷,致使常規(guī)制備的ZnO薄膜中載流子濃度會(huì)較大,使得制備的未摻雜的ZnO-TFT的關(guān)態(tài)電流較大,開(kāi)關(guān)比偏小；而現(xiàn)已報(bào)道的摻雜的ZnO基TFT性能又不夠理想。提高ZnO基TFT性能的一個(gè)關(guān)鍵是有效地調(diào)控有源層的載流子濃度。Li和N分別作為Zn和O的合適的替位者(Lizn和No),可調(diào)節(jié)ZnO中的載流子濃度,通過(guò)合理?yè)诫sLi和N,有望提高ZnO-TFT的性能。基于以上考慮,本論文主要制備了Li、N摻雜的ZnO基TFTs,并通過(guò)優(yōu)化有源層沉積條件,得到了性能優(yōu)良的ZnO基TFT。主要研究?jī)?nèi)容如下：(1)用磁控濺射在SiO2/p-Si襯底上研制出了ZnO:Li-TFT,研究了退火溫度、有源層厚度、溝道寬長(zhǎng)比對(duì)其性能的影響。實(shí)驗(yàn)結(jié)果表明,有源層厚度為30 nm,退火溫度為800℃時(shí)器件性能最佳,其遷移率為7.6 cm2/V s,開(kāi)關(guān)比為2.3×107。與Al、Mg、Ga等摻雜的ZnO-TFTs相比,其性能有所改善。(2)用磁控濺射制備了ZnO:N-TFT,研究了退火溫度、有源層厚度、溝道寬長(zhǎng)比對(duì)其性能的影響,并研究了該器件的穩(wěn)定性。實(shí)驗(yàn)結(jié)果表明,有源層厚度為30 nm,退火溫度為800℃時(shí)器件性能最佳,其遷移率為22.1 cm2/Vs,開(kāi)關(guān)比為1.1×108,開(kāi)態(tài)電流為9.4×10-3A。相比已報(bào)道的A1、Mg、Ga等摻雜的ZnO-TFTs,其性能有顯著提高；相比本征ZnO-TFTs,其開(kāi)關(guān)比也有很大改善。結(jié)果表明,該器件在空氣中放置120天仍保持較高遷移率μSAT=19.3·cm2/Vs,有較好穩(wěn)定性。(3)用磁控濺射制備了底柵極結(jié)構(gòu)的ZnO:(Li,N)-TFT。研究了退火溫度、有源層厚度、溝道寬長(zhǎng)比對(duì)其性能的影響,并探究了該器件的穩(wěn)定性。實(shí)驗(yàn)結(jié)果表明,30 nm厚的有源層800℃退火的器件性能最佳,其遷移率高達(dá)33.6 cm2/Vs,開(kāi)關(guān)比高達(dá)1.1×108,開(kāi)態(tài)電流為8.2×10-3A;相比已報(bào)道的A1、Mg、Ga等摻雜的ZnO-TFTs和本征ZnO-TFTs,其性能均有顯著提高,表現(xiàn)出Li-N共摻雜的優(yōu)越性。該器件在空氣中放置180天后,遷移率稍微降至31.2cm2/Vs,表明了器件良好的穩(wěn)定性。(4)用磁控濺射制備了未退火的ZnO:(Li,N)-TFT,研究了有源層厚度、紫外臭氧處理、氬氧氣流比以及A1203緩沖層對(duì)器件性能的影響,并探討了器件穩(wěn)定性。實(shí)驗(yàn)結(jié)果表明,有源層厚度為20 nm時(shí)器件性能最佳,其遷移率為13.5 cm2/Vs,開(kāi)關(guān)比為8.1×107,閾值電壓為7.6V。該器件在空氣中放置60天后,遷移率增大到15.7 cm2/Vs;放置120天降低到10.9 cm2/Vs,表現(xiàn)出較好的穩(wěn)定性。研究表明,增加氧氣流量和A1203緩沖層不利于ZnO:(Li,N)-TFT性能的提高,而有源層經(jīng)UV-Ozone處理后的器件性能有所提高,其遷移率為15.3 cm2/V s,開(kāi)關(guān)比為1.2×108,閾值電壓為9.9V。
[Abstract]:ZnO based TFT has attracted much attention because of its wide application prospect in flat panel display and transparent circuits. Due to the intrinsic defects such as Zn gap and O vacancy in ZnO, the carrier concentration in conventional ZnO films will be larger. The off-state current of the prepared undoped ZnO-TFT is larger and the switching ratio is smaller. One of the key points to improve the performance of ZnO based TFT is to regulate the carrier concentration of active layer. Li and N are suitable substitutes for Zn and O, respectively, which can be adjusted. Carrier concentration in ZnO, It is expected to improve the performance of ZnO-TFT by doping Li and N reasonably. Based on the above considerations, we have prepared Li-N-doped ZnO based TFTs and optimized the deposition conditions of active layers. The main research contents are as follows: (1) ZnO: Li-TFTs have been fabricated on SiO2/p-Si substrate by magnetron sputtering. The effects of annealing temperature, thickness of active layer and ratio of channel width to length on the properties of TFTs have been studied. When the thickness of active layer is 30 nm, the annealing temperature is 800 鈩，

本文編號(hào)：1660827