国产bbaaaaa片,成年美女黄网站色视频免费,成年黄大片,а天堂中文最新一区二区三区,成人精品视频一区二区三区尤物

首頁> 外文學(xué)位 >Characterization of Structural Defects in Wide Band-Gap Compound Materials for Semiconductor and Opto-Electronic Applications.
【24h】

Characterization of Structural Defects in Wide Band-Gap Compound Materials for Semiconductor and Opto-Electronic Applications.

機(jī)譯：用于半導(dǎo)體和光電應(yīng)用的寬帶隙復(fù)合材料中結(jié)構(gòu)缺陷的表征。

獲取原文
獲取原文并翻譯 | 示例
  • 摘要
  • 著錄項(xiàng)
  • 相似文獻(xiàn)
  • 相關(guān)主題

摘要

Single crystals of binary and ternary compounds are touted to replace silicon for specialized applications in the semiconductor industry. However, the relative high density of structural defects in those crystals has hampered the performance of devices built on them. In order to enhance the performance of those devices, structurally perfect single crystals must be grown. The aim of this thesis is to investigate the interplay between crystal growth process and crystal quality as well as structural defect types and transport property. To this end, the thesis is divided into two parts.;The first part provides a general review of the theory of crystal growth (chapter I), an introduction to the materials being investigated (chapter II and III) and the characterization techniques being used (chapter IV).;• In chapter I, a brief description of the theory of crystal growth is provided with an eye towards the driving force behind crystal nucleation and growth along with the kinetic factors affecting crystal growth. The case of crystal growth of silicon carbide (SiC) by physical vapor transport (PVT) and chemical vapor deposition (CVD) is discussed. The Bridgman, travelling heater method (THM) and physical transport growth of cadmium zinc telluride (CZT) is also treated. In chapters II and III, we introduce the compound materials being investigated in this study. While a description of their crystal structure and properties is provided, the issues associated with their growth are discussed. In chapter IV, a description of the characterization techniques used in these studies is presented. These techniques are synchrotron X-ray topography (SXRT), transmission electron microscopy, transmission infrared microscopy (TIM), micro-Raman spectroscopy (muRS) and light microscopy. Extensive treatment of SXRT technique is also provided.;In the second part, the experimental results obtained in the course of these studies are presented and discussed. These results are divided into three subsections.;• The development of a new technique for the production of large and high quality silicon carbide single crystal boule is proposed. This technique herein referred to as Large Tapered Crystal (LTC) growth consists of two steps: growth of long SiC rod crystal by solvent-laser heated floating zone (Solvent-LHFZ) and lateral expansion of a seed by hot wall chemical vapor deposition (HWCVD). Solvent-LHFZ was successful as SiC rod crystals, replicating the polytype structure of the starting seed, were achieved at a growth rate varying from 4 to 100mum/hr. However, SXRT revealed the presence of an inhomogeneous strain in the grown crystal rod. This was further confirmed by SEM images, which showed the platelet-like morphology of the growth front with pockets in which iron (Fe)-rich material from the Fe solvent is trapped. It was furthermore observed that at high Fe to Si ratio (∼1.9), no growth was achieved. HWCVD enlargement was also successful as SiC boules, replicating the polytype structure of the starting seed, were achieved at growth rate of about 180mum/hr. The boules had a faceted hexagonal morphology with a strain-free surface marked by steps. Combination of SXRT, TEM and muRS revealed the presence of stacking disorder in the seed (3C, 4H and 15R-SiC) that replicated in the homoepitaxial layer. The formation of the observed stacking disorder is attributed to the low energy difference between stacking configurations on the growth surface as proposed by Takahashi and Ohtani.;• The influence of structural defect type and distribution on minority carrier lifetime in 4H-SiC epilayers was investigated. Structural defect type and distribution map was obtained using SXRT, whereas minority carrier lifetime map was obtained using muPCD. Decrease in carrier lifetime observed from muPCD map was associated with specific structural defects such as low angle grain boundaries (LAGBs), stacking faults (SFs), interfacial dislocations (IDs), half loop arrays (HLAs) as well as basal plane dislocations (BPDs) pinned at TSDs. While the effect of morphological defects was mitigated, combination of defects such as microcracks, overlapping triangular defects and BPD half loops were observed to reduce carrier lifetime. Furthermore, regions of high dislocation density were associated with low carrier lifetime.;• Finally, the effect of cadmium (Cd) overpressure on the quality of cadmium zinc telluride crystal ingots was investigated for two set of samples (set 1 and 2). Overall, high resistivity single crystals were achieved. Evaluation of the crystal quality by SXRT revealed that under certain Cd overpressures and growth conditions, the quality of the grown boule improved. Similarly, transmission infrared (IR) microscopy showed a correlation between the size/density and distribution of Te inclusions/precipitates and Cd overpressure. The size of Te inclusions was observed to decrease as a function of Cd overpressure as predicted from partial pressure data for stoichiometric melt. The best improvement in crystalline quality were observed for samples from set 1at a Cd reservoir of 785 °C and for set 2 samples for a Cd reservoir at 825 °C. This difference in Cd reservoir temperature for stoichiometric growth between set 1 and set 2 was attributed to other factors such as rate of cooling of Cd reservoir, rate of cooling of the crystal along with control of the melt interface. The summary of these results and the implication of this growth approach for producing high quality CZT single crystals are discussed.
機(jī)譯：吹捧二元和三元化合物的單晶來代替硅，以用于半導(dǎo)體工業(yè)中的特殊應(yīng)用。但是，那些晶體中相對較高的結(jié)構(gòu)缺陷密度阻礙了構(gòu)建在其上的器件的性能。為了增強(qiáng)這些器件的性能，必須生長出結(jié)構(gòu)完美的單晶。本文的目的是研究晶體生長過程與晶體質(zhì)量之間的相互作用，以及結(jié)構(gòu)缺陷的類型和傳輸性能。為此，論文分為兩個(gè)部分：第一部分對晶體生長理論（第一章）進(jìn)行了綜述，介紹了所研究的材料（第二章和第三章）以及所使用的表征技術(shù)。 （第四章）；?在第一章中，簡要介紹了晶體生長理論，著眼于晶體成核和生長背后的驅(qū)動(dòng)力以及影響晶體生長的動(dòng)力學(xué)因素。討論了通過物理氣相傳輸（PVT）和化學(xué)氣相沉積（CVD）進(jìn)行碳化硅（SiC）晶體生長的情況。還處理了Bridgman，行進(jìn)加熱器法（THM）和碲化鎘鋅（CZT）的物理遷移生長。在第二章和第三章中，我們介紹了本研究中要研究的復(fù)合材料。雖然提供了其晶體結(jié)構(gòu)和性能的描述，但討論了與其生長相關(guān)的問題。第四章介紹了這些研究中使用的表征技術(shù)。這些技術(shù)是同步加速器X射線形貌（SXRT），透射電子顯微鏡，透射紅外顯微鏡（TIM），顯微拉曼光譜（muRS）和光學(xué)顯微鏡。第二部分介紹并討論了在這些研究過程中獲得的實(shí)驗(yàn)結(jié)果。這些結(jié)果分為三個(gè)小節(jié)。?提出了一種用于生產(chǎn)大型和高質(zhì)量碳化硅單晶晶錠的新技術(shù)的開發(fā)。此技術(shù)在本文中稱為大錐形晶體（LTC）生長，包括兩個(gè)步驟：通過溶劑激光加熱的浮區(qū)（Solvent-LHFZ）生長長SiC棒狀晶體，以及通過熱壁化學(xué)氣相沉積（HWCVD）進(jìn)行種子的橫向膨脹）。溶劑-LHFZ是成功的，因?yàn)镾iC棒狀晶體以4至100mum / hr的生長速率復(fù)制了起始種子的多型結(jié)構(gòu)。但是，SXRT顯示在生長的晶體棒中存在不均勻的應(yīng)變。 SEM圖像進(jìn)一步證實(shí)了這一點(diǎn)，該圖像顯示了帶有囊袋的生長前沿的片狀形態(tài)，在囊袋中捕獲了來自Fe溶劑的富含鐵（Fe）的材料。此外觀察到，在高的鐵硅比（?1.9）下，沒有獲得生長。 HWCVD的擴(kuò)大也很成功，因?yàn)镾iC圓棒以約180mum / hr的生長速度復(fù)制了起始種子的多型結(jié)構(gòu)。圓餅具有多面六邊形的形態(tài)，無應(yīng)變的表面標(biāo)有臺(tái)階。 SXRT，TEM和muRS的組合揭示了在同質(zhì)外延層中復(fù)制的種子（3C，4H和15R-SiC）中存在堆垛無序現(xiàn)象。 Takahashi和Ohtani提出，觀察到的堆垛層錯(cuò)的形成是由于生長表面上的堆垛構(gòu)型之間的能量差低。?研究了結(jié)構(gòu)缺陷類型和分布對4H-SiC外延層中少數(shù)載流子壽命的影響。使用SXRT獲得結(jié)構(gòu)缺陷類型和分布圖，而使用muPCD獲得少數(shù)載流子壽命圖。從muPCD圖觀察到的載流子壽命的減少與特定的結(jié)構(gòu)缺陷有關(guān)，例如低角度晶界（LAGB），堆垛層錯(cuò)（SF），界面位錯(cuò)（ID），半環(huán)陣列（HLA）以及基底平面位錯(cuò)（BPD） ）固定在TSD上。雖然減輕了形態(tài)缺陷的影響，但觀察到諸如微裂紋，重疊的三角形缺陷和BPD半環(huán)之類的缺陷組合會(huì)縮短載流子壽命。此外，高位錯(cuò)密度區(qū)域與低載流子壽命有關(guān)。?最后，對兩組樣品（第1組和第2組）研究了鎘（Cd）超壓對碲化鎘鋅鋅晶錠質(zhì)量的影響。總體而言，獲得了高電阻率的單晶。通過SXRT對晶體質(zhì)量的評估表明，在某些Cd超壓和生長條件下，生長的晶錠的質(zhì)量得到了改善。相似地，透射紅外（IR）顯微鏡顯示Te夾雜物/沉淀物的大小/密度和分布與Cd超壓之間的相關(guān)性。如從化學(xué)計(jì)量的熔體的分壓數(shù)據(jù)所預(yù)測的，觀察到Te夾雜物的尺寸隨著Cd超壓的減小而減小。對于一組1的樣品，在785°C的Cd儲(chǔ)層中觀察到晶體質(zhì)量的最佳改善，對于一組2的Cd儲(chǔ)藏在825°C的樣品，其結(jié)晶質(zhì)量得到最好的改善。組1和組2之間化學(xué)計(jì)量生長的Cd儲(chǔ)層溫度的差異歸因于其他因素，例如Cd儲(chǔ)層的冷卻速率，晶體的冷卻速率以及熔體界面的控制。討論了這些結(jié)果的總結(jié)以及這種生長方法對生產(chǎn)高質(zhì)量CZT單晶的意義。

著錄項(xiàng)

  • 作者

    Goue, Ouloide Yannick.;

  • 作者單位

    State University of New York at Stony Brook.;

  • 授予單位 State University of New York at Stony Brook.;
  • 學(xué)科 Materials science.
  • 學(xué)位 Ph.D.
  • 年度 2016
  • 頁碼 187 p.
  • 總頁數(shù) 187
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類
  • 關(guān)鍵詞

相似文獻(xiàn)

  • 外文文獻(xiàn)
  • 中文文獻(xiàn)
  • 專利
獲取原文

客服郵箱：kefu@zhangqiaokeyan.com

京公網(wǎng)安備：11010802029741號 ICP備案號：京ICP備15016152號-6 六維聯(lián)合信息科技 (北京) 有限公司?版權(quán)所有

  • 客服微信

  • 服務(wù)號