本文選題：氧化銦鎵鋅　切入點：霍爾遷移率　出處：《清華大學(xué)》2016年博士論文

【摘要】：非晶氧化銦鎵鋅(InGa ZnO_4,IGZO)作為一種新型的薄膜晶體管(thin film transistor,TFT)有源層材料,相比于傳統(tǒng)氫化非晶硅(a-Si:H),具有遷移率高、透過率高、均勻性好以及制備溫度低等諸多優(yōu)勢,被認(rèn)為是下一代平板顯示技術(shù)關(guān)鍵材料。本文采用磁控濺射法制備非晶IGZO薄膜,系統(tǒng)深入研究工藝參數(shù)對IGZO薄膜電學(xué)性能的影響,并分析工藝參數(shù)對IGZO薄膜載流子濃度與Hall遷移率的作用機制。針對IGZO薄膜載流子輸運特性進行重點研究,揭示影響遷移率大小的內(nèi)在本質(zhì),同時提出對滲流傳導(dǎo)模型的修正。在此基礎(chǔ)上,首次提出用Nb元素替代Ga元素,設(shè)計并制備INZO薄膜,進一步提高Hall遷移率,降低與TFT器件穩(wěn)定性相關(guān)的深能級隙態(tài)缺陷。本文主要研究內(nèi)容和成果如下:系統(tǒng)深入地研究了濺射電流、氧氣流量、基底溫度以及退火溫度對IGZO薄膜載流子濃度和Hall遷移率的影響,揭示其作用機制。載流子濃度主要取決于作為施主型缺陷的氧空位的數(shù)量。Hall遷移率受載流子濃度與微觀結(jié)構(gòu)兩方面因素共同作用。載流子濃度、結(jié)構(gòu)無序程度的變化,均會改變勢壘起伏對載流子的散射作用,從而影響薄膜Hall遷移率。在優(yōu)化工藝條件下,制備得到了高質(zhì)量的IGZO薄膜,在符合TFT器件制備要求的載流子濃度范圍內(nèi)(6.01×10~(16) cm~(-3)),最高Hall遷移率達(dá)19.1 cm~2·V~(-1)·s~(-1),為非晶硅的近20倍;針對IGZO薄膜載流子輸運特性進行系統(tǒng)研究,揭示載流子輸運機制為滲流傳導(dǎo)。引入勢壘寬度因子對滲流傳導(dǎo)數(shù)學(xué)模型進行修正,提出本征遷移率可表示為能量高于勢壘起伏的電子所具有的遷移率與勢壘寬度因子的乘積。IGZO薄膜Hall遷移率變化的內(nèi)在本質(zhì)為勢阱寬度的改變以及平均勢壘高度的改變。通過光致發(fā)光技術(shù)對IGZO薄膜深能級隙態(tài)缺陷進行表征,分析并揭示了各發(fā)光峰的激發(fā)機制與發(fā)射機制。結(jié)果表明,529 nm與698 nm處的發(fā)光與氧空位深能級缺陷相關(guān),發(fā)光源于電子從導(dǎo)帶或?qū)矐B(tài)至氧空位缺陷的輻射躍遷。提出用Nb元素替代Ga元素設(shè)計并制備INZO薄膜,系統(tǒng)研究氧氣流量與基底溫度對INZO載流子濃度與Hall遷移率的影響并分析作用機制。研究表明,INZO薄膜Hall遷移率較高源于勢阱寬度較寬以及勢壘高度較小,深能級隙態(tài)缺陷較少則源于Nb對氧空位的抑制。在優(yōu)化工藝條件下制備得到了高質(zhì)量的INZO薄膜。在載流子濃度為10~(19)~10~(20) cm~(-3)范圍內(nèi),INZO最高Hall遷移率為45.0 cm~2·V~(-1)·s~(-1)。
[Abstract]:As a new type of thin film transistor film transistor-TFT-based active layer material, InGaO4ZO has many advantages, such as high mobility, high transmittance, good uniformity and low preparation temperature, compared with conventional hydrogenated amorphous silicon.It is considered to be the key material of the next generation flat panel display technology.Amorphous IGZO thin films were prepared by magnetron sputtering. The effects of process parameters on the electrical properties of IGZO thin films were studied systematically. The mechanism of the effects of process parameters on the carrier concentration and Hall mobility of IGZO thin films was analyzed.The carrier transport characteristics of IGZO thin films are studied in order to reveal the intrinsic nature of the mobility and the modification of the percolation conduction model is proposed.On this basis, the NB element is used to replace Ga element for the first time to design and prepare INZO thin films, which can further improve the Hall mobility and reduce the deep level gap state defects related to the stability of TFT devices.The main contents and achievements are as follows: the effects of sputtering current, oxygen flow rate, substrate temperature and annealing temperature on the carrier concentration and Hall mobility of IGZO thin films have been investigated.The carrier concentration mainly depends on the number of oxygen vacancies as donor defects. Hall mobility is affected by both carrier concentration and microstructure.The variation of carrier concentration and structure disorder will change the scattering effect of barrier fluctuations on the carriers and thus affect the Hall mobility of the films.A high quality IGZO thin film was prepared under the optimized conditions. In the carrier concentration range of 6.01 脳 10 ~ (-1) ~ (16) cm ~ (-1) ~ (-1) TFT, the highest Hall migration rate was 19.1 cm~2 ~ (-1) ~ (-1) Si ~ (-1), which was about 20 times of that of amorphous silicon.The characteristics of carrier transport in IGZO thin films are systematically studied, and it is revealed that the carrier transport mechanism is percolation conduction.Introducing the barrier width factor to modify the mathematical model of seepage conduction,It is proposed that the intrinsic mobility can be expressed as the product of energy higher than the barrier fluctuation and the product of barrier width factor. The intrinsic essence of the Hall mobility change of IGZO thin films is the change of the potential well width and the average barrier height.The deep level gap state defects of IGZO thin films were characterized by photoluminescence technique. The excitation and emission mechanisms of each luminescence peak were analyzed and revealed.The results show that the luminescence at 529 nm and 698 nm is related to the deep level defect of oxygen vacancy, and the luminescence results from the radiative transition of electron from the tail state of conduction band or conduction band to the defect of oxygen vacancy.INZO thin films were designed and prepared by NB instead of Ga. The effects of oxygen flow rate and substrate temperature on INZO carrier concentration and Hall mobility were systematically studied and the mechanism of action was analyzed.The results show that the higher Hall mobility of Inzo thin films is due to the wide potential well width and the lower barrier height, and the lower defects in deep level gap states are due to the inhibition of oxygen vacancies by NB.High quality INZO thin films were prepared under optimized conditions.The highest Hall mobility is 45.0 cm~2 / v ~ (-1) ~ (-1) in the carrier concentration range of 10 ~ 19 ~ 10 ~ 10 ~ 10 ~ (-1) cm ~ (-1) ~ (-1) ~ (-1) ~ (-1) ~ (-1) ~ (-1) 路cm ~ (-1) ~ (-1) ~ (-1)).
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TN304.055;TN321.5

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