光電子技術(shù)專業(yè)英語(yǔ)

1、光電子技術(shù) 專業(yè)英語(yǔ),Contents,,Chapter 1 科技英語(yǔ)翻譯,,,,Chapter 2 Semiconductor Physics & Device,,Chapter 3 Electromagnetic Field & Electromagnetic Wave,,Chapter 4 Fundamentals of Optics,,,,,,Chapter 7 I

2、ntegrated Circuit Fabrication,,Chapter 8 Optical Communications,,,,,Chapter 10 Optical Tweezers,,Chapter 11 Photonic Crystal Fiber,,Chapter 12 科技文獻(xiàn)檢索,,,,Chapter 13 國(guó)內(nèi)核心期刊檢索及國(guó)際三大檢索,,Chapter 14 英語(yǔ)科技論文寫作,,Chapter 15 Coher

3、ent Optical Information Systems,Chapter 5 Fundamentals of Lasers,Chapter 9 Holographic Data Storage,Chapter 6 Nonlinear Optics,第1章 科技英語(yǔ)翻譯,學(xué)習(xí)專業(yè)英語(yǔ)不僅僅是學(xué)習(xí)英語(yǔ)專業(yè)詞匯，在科技英語(yǔ)中，專業(yè)詞匯僅占20%，其余80%都是我們常用的詞匯?？萍加⒄Z(yǔ)主要應(yīng)用于科技報(bào)告和論文的寫作中，在表

4、達(dá)上具有簡(jiǎn)潔、準(zhǔn)確的特點(diǎn)，這使得科技英語(yǔ)在語(yǔ)法上具有一定的特殊性。我們將對(duì)科技英語(yǔ)的概念、文體總貌、詞匯特點(diǎn)、翻譯方法和技巧等方面進(jìn)行簡(jiǎn)單闡述，以盡快適應(yīng)專業(yè)英語(yǔ)的學(xué)習(xí)。,第1章 科技英語(yǔ)翻譯,1.1 科技英語(yǔ)的概念科技英語(yǔ)泛指一切論及或談及科學(xué)和技術(shù)的書面語(yǔ)和口語(yǔ)，其中包括：一、科技著述、科技論文和報(bào)告、實(shí)驗(yàn)報(bào)告和方案；二、各類科技情報(bào)和文字資料；三、科技實(shí)用手冊(cè)的結(jié)構(gòu)描述和操作規(guī)程；四、有關(guān)科技問(wèn)題的會(huì)談、會(huì)議、交談?dòng)谜Z(yǔ)；五、

5、有關(guān)科技的影片、錄像、光盤等有聲資料的解說(shuō)詞等等。1.2科技英語(yǔ)文體總貌 科技英語(yǔ)要求客觀性、準(zhǔn)確性和嚴(yán)密性，注重?cái)⑹逻壿嬌系倪B貫(Coherence)及表達(dá)上的明晰(Clarity)與暢達(dá)(Fluency)，避免行文晦澀。 科技英語(yǔ)力求平易(Plainness)和精確(Preciseness)，避免使用旨在加強(qiáng)語(yǔ)言感染力和宣傳效果的各種修辭格,,,,第1章 科技英語(yǔ)翻譯,,,,3. 半專業(yè)詞匯 指那些既用于日常英語(yǔ)，同時(shí)又是科技

6、英語(yǔ)中常用的詞匯。,,1.3 科技英語(yǔ)詞匯特點(diǎn),4. 新詞匯 近幾十年來(lái)，在現(xiàn)有專業(yè)詞匯和半專業(yè)詞匯的基礎(chǔ)上又出現(xiàn)了幾種新的詞匯，其構(gòu)詞方法主要有合成法、混成法、截短法、縮略法、轉(zhuǎn)化法等。,,1. 日常詞匯 用于某一專業(yè)科技領(lǐng)域便成為專業(yè)技術(shù)用語(yǔ)，具有嚴(yán)格的科學(xué)含義。 .,,2. 專業(yè)詞匯 除部分來(lái)自英語(yǔ)日常詞匯外，絕大多數(shù)，尤其是名詞術(shù)語(yǔ)則是由拉丁語(yǔ)和希臘語(yǔ)的詞根(root)和詞綴（affix）構(gòu)成的。,第1章 科技英語(yǔ)翻譯,1.4

7、科技英語(yǔ)翻譯翻譯是把一種語(yǔ)言所表達(dá)的思維內(nèi)容用另一種語(yǔ)言表達(dá)出來(lái)的跨語(yǔ)言、跨文化的語(yǔ)言交際活動(dòng)。翻譯包括口譯(interpretation)和筆譯(translation)。在筆譯中，又可分為科技翻譯、文學(xué)翻譯、政論文翻譯和應(yīng)用文翻譯等等。1.4.1科技英語(yǔ)翻譯標(biāo)準(zhǔn) 關(guān)于翻譯標(biāo)準(zhǔn)曾有過(guò)“信、達(dá)、雅”，“信、順”， “忠實(shí)、通順、易懂”，“等值”等等多種提法。許多翻譯工作者和研究者也曾對(duì)這些提法展開(kāi)過(guò)廣泛而激烈的爭(zhēng)論和討論。但就科技

8、英語(yǔ)翻譯而言，我們可以把翻譯標(biāo)準(zhǔn)概括為忠實(shí)原作和譯文通順。1. 忠實(shí) 譯文應(yīng)忠實(shí)于原文，準(zhǔn)確地、完整地、科學(xué)地表達(dá)原文的內(nèi)容，包括思想、精神與風(fēng)格。譯者不得任意對(duì)原文內(nèi)容加以歪曲、增刪、遺漏和篡改。2. 通順 譯文語(yǔ)言必須通順，符合規(guī)范，用詞造句應(yīng)符合本民族語(yǔ)言的習(xí)慣，要用民族的、科學(xué)的、大眾的語(yǔ)言，以求通順易懂。不應(yīng)有文理不通、逐詞死譯和生硬晦澀等現(xiàn)象。,第1章 科技英語(yǔ)翻譯,1.4.2 科技英語(yǔ)翻譯過(guò)程中語(yǔ)法特點(diǎn)大量

9、使用名詞化結(jié)構(gòu) 多用動(dòng)詞的現(xiàn)在時(shí) can和may使用頻率高 廣泛使用被動(dòng)語(yǔ)句 非限定動(dòng)詞的應(yīng)用和大量使用后置定語(yǔ) 大量使用常用句型 使用長(zhǎng)句 大量使用復(fù)合詞與縮略詞,第1章 科技英語(yǔ)翻譯,1.4.3 科技英語(yǔ)的翻譯方法與技巧 翻譯技巧一般包括改變?cè)~類(conversion)、詞序調(diào)整(inversion)、省略(omission)、增詞(amplification)、重復(fù)(repetition)、反譯法(negatio

10、n)、選詞用字(diction)、和分譯法(division)、 綜合法（Recasting）和語(yǔ)篇重構(gòu)等等。 1. 詞類轉(zhuǎn)換 將英語(yǔ)句子中屬于某種詞類的詞，譯成另一種詞類的漢語(yǔ)詞，以適應(yīng)漢語(yǔ)的表達(dá)習(xí)慣或達(dá)到某種修辭目的。 如：（1）Lasers are used in the treatment of retinal detachment.激光用于治療視網(wǎng)膜脫落?！爸委焧reat”因作介詞賓語(yǔ)需用名詞treatment

11、，漢譯時(shí)仍可用動(dòng)詞“治療”。 （2）Maiman’s invention of the laser provided new sources of very intense, coherent and highly directional light beams.梅曼發(fā)明了激光器，提供了一種新光源，可產(chǎn)生極強(qiáng)的、相干的和高度定向的光束?！鞍l(fā)明”英譯時(shí)因作主語(yǔ)故用名詞invention。,第1章 科技英語(yǔ)翻譯,1.4.3

12、科技英語(yǔ)的翻譯方法與技巧 2. 詞序調(diào)整 有時(shí)候英語(yǔ)長(zhǎng)句的敘述層次與漢語(yǔ)相反，這時(shí)就須從英語(yǔ)原文的后面譯起，自上而下，逆著英語(yǔ)原文的順序翻譯。翻譯時(shí)應(yīng)根據(jù)TL的表達(dá)方式作一些有必要的調(diào)整中。 如：Ningbo, China, August 2, 2009 - China outclassed Russia in a hard-fought five-set match on Sunday in the 2009 FIVB Wo

13、rld Grand Prix. (地點(diǎn)在前)2009年8月2日，在中國(guó)寧波舉行的一場(chǎng)2009世界女排大獎(jiǎng)賽的一場(chǎng)比賽中，中國(guó)隊(duì)經(jīng)過(guò)五局苦戰(zhàn)，以3:2戰(zhàn)勝俄羅斯隊(duì)。(時(shí)間在前) 3. 增減詞譯法由于兩種語(yǔ)言表達(dá)方式不同，在把原文信息譯成譯文信息時(shí)，常常需要?jiǎng)h去或增添一些詞。這樣做并不損害原意，反而可以使譯文更為通順，意思更為清楚。如：You cannot build a ship, a bridge or a house i

14、f you don’t know how to make a design or how to read it.不會(huì)制圖或看不懂圖紙，就不可能造船、架橋或蓋房子。漢譯中省略代詞you和it、冠詞a、連接詞if和副詞how。,第1章 科技英語(yǔ)翻譯,1.4.3 科技英語(yǔ)的翻譯方法與技巧 4. 重復(fù) 英語(yǔ)為了避免重復(fù)常常用一個(gè)動(dòng)詞接幾個(gè)賓語(yǔ)或表語(yǔ)；或用了一個(gè)動(dòng)詞，后面相同的動(dòng)詞便可以省略；或大量使用代詞以避免重復(fù)名詞。漢語(yǔ)不怕重復(fù)，遇到

15、上述情況漢譯時(shí)可以采用重復(fù)某詞的手法 。 如：I had experienced oxygen and/or engine trouble.我曾碰到過(guò)，不是氧氣設(shè)備出故障，就是引擎出故障，或兩者都出故障。本例屬名詞的重復(fù)。5. 反譯法 由于漢英兩種語(yǔ)言表達(dá)習(xí)慣不同而且均可以從正面或反面來(lái)表達(dá)同一概念，翻譯時(shí)如果用正面表達(dá)譯文有困難，欠通順，則不妨用反面表達(dá)，或?qū)⒎疵姹磉_(dá)改用正面表達(dá)，這樣可以使譯文比較通順而與原意并無(wú)出入。

16、如：I lay awake almost the whole night.我?guī)缀跻灰箾](méi)睡著。例屬正說(shuō)反譯。 I can’t agree with you more.我極其贊同你的意見(jiàn)。本例屬反說(shuō)正譯。,第1章 科技英語(yǔ)翻譯,1.4.3 科技英語(yǔ)的翻譯方法與技巧 6. 選詞用字 由于構(gòu)詞時(shí)聯(lián)想不同，表達(dá)方式不同，兩種語(yǔ)言表達(dá)同一種思想常常用詞不同。因而在翻譯時(shí)必須在理解原意的基礎(chǔ)上，考慮表達(dá)這個(gè)意思的TL要用什么詞最

17、為恰當(dāng)。如： It caused devastation by burrowing and by devouring the herbage which might have maintained millions of sheep and cattle.它們?cè)诘叵麓蚨?，吞食掉本?lái)可以維持?jǐn)?shù)百萬(wàn)只牛羊的牧草，從而造成了破壞。 原文中的cattle有“牲畜”和“牛”二義，這里因與“羊”(sheep)對(duì)置，根據(jù)種屬概念不能并列的邏輯規(guī)

18、則，cattle只能作“牛”解。7. 分譯法 英語(yǔ)長(zhǎng)句比較多，有時(shí)英語(yǔ)長(zhǎng)句中主句與從句或主句與修飾語(yǔ)間的關(guān)系不十分密切，翻譯時(shí)可按照漢語(yǔ)多用短句的習(xí)慣，把長(zhǎng)句中的從句或短語(yǔ)化為句子，分開(kāi)來(lái)敘述，將原句化整為零。為使譯文通順連貫，也可以適當(dāng)加幾個(gè)連接詞。如：The number of the young people in the United States who can’t read is incredible about

19、one in four.大約有1/4的美國(guó)青年人沒(méi)有閱讀能力，這簡(jiǎn)直令人難以置信。該句在英語(yǔ)中是一個(gè)相對(duì)簡(jiǎn)單的句子，但是如果我們按照原文的句子結(jié)構(gòu)死譯，就可能被翻譯成：沒(méi)有閱讀能力的美國(guó)青年人的數(shù)目令人難以相信約為1/4。這樣，就使得譯文極為不通順，不符合漢語(yǔ)的表達(dá)習(xí)慣。,第1章 科技英語(yǔ)翻譯,1.4.3 科技英語(yǔ)的翻譯方法與技巧 8. 綜合法 對(duì)那些用某種翻譯技巧無(wú)法譯出時(shí)，著眼于篇章，以邏輯分析為基礎(chǔ)，有順有序，有主有次對(duì)全句

20、進(jìn)行綜合處理 。 如：Many man-made substances are replacing certain natural materials because either the quantity of the natural product can not meet our ever-increasing requirement, or, more often, because the physical property

21、 of the synthetic substance, which is the common name for man-made materials, has been chosen, and ever emphasized, so that it would be of the greatest use in the fields in which it is to be applied.這個(gè)句子是由一個(gè)主句加上一個(gè)由beca

22、use引導(dǎo)的原因狀語(yǔ)從句，一個(gè)由 so that 引導(dǎo)的狀語(yǔ)從句和which 引導(dǎo)的非限制性定語(yǔ)從句及 in which 引導(dǎo)的定語(yǔ)從句所組成。譯文：人造材料統(tǒng)稱為合成材料，許多人造材料正在替代某些天然材料，這或者是由于天然產(chǎn)品的數(shù)量不能滿足日益增長(zhǎng)的需要，或者往往是人們選擇了合成材料的一些物理性質(zhì)并加以突出而造成的。因此合成材料在應(yīng)用的領(lǐng)域中將具有極大的用途。9. 語(yǔ)篇重構(gòu) 語(yǔ)篇重構(gòu)就是對(duì)原文的結(jié)構(gòu)和語(yǔ)言進(jìn)行較大幅度的改動(dòng)，脫離

23、原句的層次和結(jié)構(gòu)安排，按漢語(yǔ)敘事倫理的習(xí)慣重新組合句子，擺脫了原文的語(yǔ)序和句子形式的約束，使譯文自然、流暢，更加符合漢語(yǔ)的表達(dá)習(xí)慣，以期在更深的層次上達(dá)到與原文的對(duì)等。如：Computer languages may range from detailed low level close to that immediately understood by the particular computer, to the sophist

24、icated high level which can be rendered automatically acceptable to a wide range of computers.譯文：計(jì)算機(jī)語(yǔ)言有低級(jí)的也有高級(jí)的。前者比較煩瑣，很接近特定計(jì)算機(jī)直接能動(dòng)的語(yǔ)言；后者比較復(fù)雜，適用范圍廣，能自動(dòng)為多種計(jì)算機(jī)所接受。,第1章 科技英語(yǔ)翻譯,1.5 提高科技英語(yǔ)翻譯能力的途徑 對(duì)于廣大英語(yǔ)學(xué)習(xí)者來(lái)說(shuō)，要想具有上述素質(zhì)當(dāng)然不可能一蹴

25、而就，但只要努力，將來(lái)就一定能夠成功。下面列出了幾種提高科技英語(yǔ)翻譯的途徑，以供參考。1. 廣泛閱讀英漢報(bào)刊雜志，提高英漢兩種語(yǔ)言基本功。2. 廣泛涉獵中英文科技文章和新聞，有效地?cái)U(kuò)展自己的知識(shí)面。 3. 認(rèn)真學(xué)習(xí)本專業(yè)的基礎(chǔ)課程和大量閱讀本專業(yè)的中英文文獻(xiàn)，提高自身的專業(yè)水平。4. 認(rèn)真學(xué)習(xí)有關(guān)科技英語(yǔ)翻譯著作和刊物，切實(shí)掌握科技英語(yǔ)翻譯方法和技巧，深入認(rèn)識(shí)科技翻譯中經(jīng)常會(huì)遇到的問(wèn)題。 5. 在翻譯實(shí)踐中提高。正如

26、其他語(yǔ)言學(xué)習(xí)一樣，學(xué)習(xí)翻譯，尤其是在打基礎(chǔ)的階段，實(shí)踐是極其重要的。 定時(shí)定量翻譯工作程序 ：第一步：快速瀏覽原文一遍，了解文章大意即可。遇到生詞除十分必要的以外都不要去查詞典，可以在下面劃線標(biāo)出。第二步，邊看邊譯，每次處理一個(gè)自然段(如段落長(zhǎng)，一次五六行左右)。具體步驟為：閱讀原文，查閱詞典，斟酌措辭，寫下譯文。如果有的地方一時(shí)還理解不好或找不到適當(dāng)?shù)谋磉_(dá)方式，可以暫時(shí)空下，做個(gè)記號(hào)，等譯完初稿后再補(bǔ)上。每段譯文寫下來(lái)后隨

27、手做些修改。有的地方一時(shí)修改不好就放下，但要在旁邊做個(gè)記號(hào)。第三步，初稿完成后即進(jìn)行修改。首先是把空下來(lái)未譯的地方補(bǔ)上，把原來(lái)未修改好的地方再修改一下。然后，從頭再閱讀一遍譯文，修改錯(cuò)別字以及語(yǔ)句不通順的地方。,第1章 科技英語(yǔ)翻譯,1.5 提高科技英語(yǔ)翻譯能力的途徑 要想在質(zhì)量上提高，學(xué)習(xí)者在平時(shí)的科技翻譯學(xué)習(xí)和實(shí)踐中就應(yīng)自覺(jué)運(yùn)用已經(jīng)學(xué)過(guò)的翻譯知識(shí)、方法和技巧，防止重犯在過(guò)去的實(shí)踐中曾經(jīng)出現(xiàn)過(guò)的失誤。因此，廣大學(xué)

28、習(xí)者應(yīng)認(rèn)真理解原文，對(duì)漢語(yǔ)表達(dá)字斟句酌，不厭其煩地反復(fù)修改。譯文的質(zhì)量沒(méi)有止境，只有反反復(fù)復(fù)地修改才會(huì)發(fā)現(xiàn)自己存在的問(wèn)題，從而提高翻譯能力。修改本身就是個(gè)提高的過(guò)程，學(xué)習(xí)者不應(yīng)該怕費(fèi)事。另外，學(xué)習(xí)者也可翻譯配有譯文的原文，把自己的譯文同所配譯文相比較，找出差距和不足，這樣也將有助于提高翻譯質(zhì)量。,Chapter 2 Semiconductor Physics and Device,PREVIEW We often hear th

29、at we are living in the information age. Large amounts of information can be obtained via the Internet, for example, and can also be obtained quickly over long distances via satellite communication system. The

30、development of the transistor and the integrated circuit (IC) has lead to these remarkable capabilities.,2.1 Semiconductor Materials Semiconductors are special crystalline materials that have electrical conductivi

31、ty (and the corresponding resistivity) between that of a conductor and an insulator. Insulators such as fused quartz and glass have very low conductivities, in the order of 1E-18 to 1E-8 S/cm; and conductors such as alum

32、inum and silver have high conductivities, typically from 104 to 106 S/cm.,Chapter 2 Semiconductor Physics and Device,2.1 Semiconductor Materials The study of semiconductor materials began in the early nineteenth c

33、entury. Over the years many semiconductors have been investigated.,Chapter 2 Semiconductor Physics and Device,2.1 Semiconductor Materials Two general classifications of semiconductors are the elemental semiconduct

34、or materials and the compound semiconductor materials.,Chapter 2 Semiconductor Physics and Device,Chapter 2 Semiconductor Physics and Device,2.1 Semiconductor MaterialsTable 2-1 A portion of the periodic table related t

35、o semiconductors,Chapter 2 Semiconductor Physics and Device,2.1 Semiconductor MaterialsTable 2-2 A list of some semiconductor materials,2.1 Semiconductor Materials Although we do not know as much about the techno

36、logy of compound semiconductor technology as we do about that of silicon, compound semiconductor technology has advanced partly because of the advances in silicon technology.,Chapter 2 Semiconductor Physics and Device,2.

37、2 Type of Solids Amorphous, polycrystalline, and single crystal are the three general types of solids. Each type is characterized by the size of an ordered region within the material.,Chapter 2 Semiconductor Physi

38、cs and Device,2.2 Type of Solids■ An ordered region is a spatial volume in which atoms or molecules have a regular geometric arrangement or periodicity. ■ The single-crystal regions are called grains and are se

39、parated from one another by grain boundaries,Chapter 2 Semiconductor Physics and Device,2.2 Type of Solids The advantage of a single-crystal material is that, in general, its electrical properties are superior to

40、those of a nonsingle-crystal material, since grain boundaries tend to degrade the electrical characteristics.,Chapter 2 Semiconductor Physics and Device,(a) amorphous (b) polycrystalline (c) single crystalFigure 2-1 S

41、chematics of three general types of crystals.,Chapter 2 Semiconductor Physics and Device,2.3 Crystal Structure The semiconductor materials we will study are single crystals, that is, the atoms are arranged in a th

42、ree-dimensional periodic fashion.,Chapter 2 Semiconductor Physics and Device,2.3 Crystal StructureThe periodic arrangement of atoms in a crystal is called a lattice In a crystal, an atom never strays far from a single,

43、 fixed position. The element semiconductors, such as silicon and germanium, have a diamond lattice structure.,Chapter 2 Semiconductor Physics and Device,2.3 Crystal Structure A convenient method of defining the v

44、arious planes in a crystal is to use Miller indices. These indices are obtained using the following steps:,Chapter 2 Semiconductor Physics and Device,2.3 Crystal Structure（1）Find the intercepts of the plane on the three

45、 Cartesian coordinates in terms of the lattice constant.（2）Take the reciprocals of these numbers and reduce them to the smallest three integers having the same ratio.（3）Enclose the result in parentheses (hkl) as the Mi

46、ller indices for a single plane.,Chapter 2 Semiconductor Physics and Device,2.4 The Atomic Structure of SemiconductorsElectronic devices such as diode and transistors are constructed from special materials called semico

47、nductors. In this section, you will learn about the atomic structure of semiconductors,Chapter 2 Semiconductor Physics and Device,2.4.1 Electron Shells and Orbits The electrical properties of materials are expl

48、ained by their atomic structure. In the early part of the 20th century, Neils Bohr, a Danish physicist, developed a model of the atom that showed electrons orbiting the nucleus.,Chapter 2 Semiconductor Physics and Device

49、,2.4.1 Electron Shells and Orbits Energy is the ability to do work and is subdivided into potential (position), kinetic (motion), and rest (mass).,Chapter 2 Semiconductor Physics and Device,2.4.2 Valence electr

50、ons, Conduction Electrons, and Ions Electrons in orbits farther from the nucleus are less tightly bound to the atom than those closer to the nucleus.,Chapter 2 Semiconductor Physics and Device,2.4.2 Valence electro

51、ns, Conduction Electrons, and Ions An electron that is in the outermost shell is called a valence electron; valence electrons have the highest energy and are relatively loosely bound to their parent atom.,Chapter 2

52、 Semiconductor Physics and Device,2.4.2 Valence electrons, Conduction Electrons, and Ions Sometimes, a valence electron can acquire enough energy to break free of its parent atom.,Chapter 2 Semiconductor Physic

53、s and Device,2.4.2 Valence electrons, Conduction Electrons, and Ions Electrons in orbits farther from the nucleus are less tightly bound to the atom than those closer to the nucleus.,Chapter 2 Semiconductor Physic

54、s and Device,2.4.3 Metallic Bands Metals tend to be solids at room temperature. The nucleus and inner-shell electrons of metals occupy fixed lattice positions.,Chapter 2 Semiconductor Physics and Device,2.4.3 M

55、etallic Bands With the large number of atoms in the metallic crystal, the discrete energy level for the valence electrons is blurred into a band called the valence band,Chapter 2 Semiconductor Physics and Devic

56、e,,Chapter 2 Semiconductor Physics and Device,Figure 2-4 Energy level diagrams for three types of materials. The upper level is the conduction band; the lower level is the valence band.,2.4.4 Covalent Bonds Atoms of s

57、ome solid materials form crystals, which are three-dimensional structures held together by strong bonds between the atoms. The shared electrons are not mobile; each electron is associated by a covalent bond between the

58、atoms of the crystal. Electronic devices are constructed from materials called semiconductors. The important difference between a conductor and a semiconductor is the gap that separates the bands.,Chapter 2 Semiconduct

59、or Physics and Device,2.4.5 Electrons and Hole CurrentWhen an electron jumps to the conduction band, a vacancy36 is left in the valence band. This vacancy is called a hole37. A piece of intrinsic39 (pure) silicon at r

60、oom temperature has, at any instant, a number of conduction-band (free) electrons that are unattached to any atom and are essentially drifting randomly throughout the material.,Chapter 2 Semiconductor Physics and Device,

61、When a voltage is applied across a piece of intrinsic silicon, as shown in Fig. 2-5, the thermally generated free electrons in the conduction band are easily attracted toward the positive end.,Chapter 2 Semiconductor Phy

62、sics and Device,2.5 The PN Junction Intrinsic silicon is not a good conductor. By adding a small amount of impurity to the silicon crystal, its electrical properties can be changed dramatically.,Chapter 2 Semicond

63、uctor Physics and Device,2.5.1 Doping The conductivity of silicon (or germanium) can be drastically increased by the controlled addition of impurities to the pure (intrinsic) semiconductive material. To increase the nu

64、mber of conduction-band electrons in pure silicon, a controlled number of pentavalent impurity atoms called donors are added to the silicon crystal.,Chapter 2 Semiconductor Physics and Device,2.5.1 Doping To increase th

65、e number of holes in pure silicon, trivalent impurity atoms called acceptorsare added during manufacture.The process of creating n-type or p-type materials retains the overall electrical neutrality.,Chapter 2 Semiconduc

66、tor Physics and Device,2.5.2 The PN Junction When a piece of intrinsic silicon is doped so that half is n type and the other half is p type, a pn junction is formed between the two regions.,Chapter 2 Semiconduc

67、tor Physics and Device,2.5.3 The Depletion Region When the pn junction is formed, some of the conduction electrons near the junction drift across into the p region and recombine with holes near the junction, a

68、s shown in Fig. 2-7 (a).,Chapter 2 Semiconductor Physics and Device,2.5.3 The Depletion Region,Chapter 2 Semiconductor Physics and Device,2.6 Biasing the Semiconductor Diode A single pn junction forms a semiconduc