【二(er)極(ji)管的作(zuo)(zuo)用】二(er)極(ji)管在電路中有什么作(zuo)(zuo)用 二(er)極(ji)管的特性有哪些(xie)

二極管在電路中有什么作用

二極管是電子元件當中一(yi)種具有兩個電(dian)(dian)(dian)(dian)(dian)極(ji)的裝置(zhi)，只(zhi)允許(xu)(xu)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)由單一(yi)方(fang)向流(liu)(liu)過，許(xu)(xu)多的使用是應用其(qi)整流(liu)(liu)的功能。而(er)變容二(er)(er)極(ji)管(guan)則用來當作電(dian)(dian)(dian)(dian)(dian)子式(shi)的可調電(dian)(dian)(dian)(dian)(dian)容器。大部分二(er)(er)極(ji)管(guan)所具備的電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)方(fang)向性我們(men)通(tong)常稱之為“整流(liu)(liu)”功能。二(er)(er)極(ji)管(guan)最普(pu)遍的功能就是只(zhi)允許(xu)(xu)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)由單一(yi)方(fang)向通(tong)過（稱為順向偏(pian)(pian)壓(ya)），反(fan)向時(shi)阻斷 （稱為逆向偏(pian)(pian)壓(ya)）。因此(ci)，二(er)(er)極(ji)管(guan)可以想成電(dian)(dian)(dian)(dian)(dian)子版(ban)的逆止閥。

該圖片由注冊用戶"橘子de殿堂"提供，版權聲明反饋

二極管是最常用的電子元件之一，它最大的特性就是單向導電，也就是電流只可以從二極管的一個方向流過，二極管的作用有整流電路，檢波電路，穩壓電路，各種調制電路，主要都是由二極管來構成的，其原理都很簡單，正是由于二極管等元件的發明，才有我們現在豐富多彩的電子信息世界的誕生，既然二極管的作用這么大那么我們應該如何去檢測這個元件呢，其實很簡單只要用萬用表打到電阻檔測量一下反向電阻如果很小就說明這個二極管是壞的(de)，反向電阻如果很大這(zhe)就說明這(zhe)個二(er)極管是好的(de)。

二極管的特性有哪些

正向性

外加(jia)正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)壓(ya)(ya)時，在(zai)正(zheng)(zheng)(zheng)(zheng)向特性的(de)(de)起(qi)始部(bu)分，正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)壓(ya)(ya)很小(xiao)，不足以克服PN結(jie)(jie)內電(dian)(dian)場(chang)的(de)(de)阻(zu)擋作用，正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)流(liu)幾乎為(wei)(wei)零，這(zhe)一段(duan)稱(cheng)為(wei)(wei)死區。這(zhe)個不能(neng)使二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)導(dao)通(tong)(tong)的(de)(de)正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)壓(ya)(ya)稱(cheng)為(wei)(wei)死區電(dian)(dian)壓(ya)(ya)。當正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)壓(ya)(ya)大于死區電(dian)(dian)壓(ya)(ya)以后，PN結(jie)(jie)內電(dian)(dian)場(chang)被克服，二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)正(zheng)(zheng)(zheng)(zheng)向導(dao)通(tong)(tong)，電(dian)(dian)流(liu)隨電(dian)(dian)壓(ya)(ya)增大而迅(xun)速上升。在(zai)正(zheng)(zheng)(zheng)(zheng)常使用的(de)(de)電(dian)(dian)流(liu)范圍內，導(dao)通(tong)(tong)時二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)的(de)(de)端電(dian)(dian)壓(ya)(ya)幾乎維持不變，這(zhe)個電(dian)(dian)壓(ya)(ya)稱(cheng)為(wei)(wei)二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)的(de)(de)正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)壓(ya)(ya)。當二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)兩(liang)端的(de)(de)正(zheng)(zheng)(zheng)(zheng)向電(dian)(dian)壓(ya)(ya)超過一定數值(zhi)，內電(dian)(dian)場(chang)很快(kuai)被削弱，特性電(dian)(dian)流(liu)迅(xun)速增長，二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)正(zheng)(zheng)(zheng)(zheng)向導(dao)通(tong)(tong)。叫做門(men)坎(kan)電(dian)(dian)壓(ya)(ya)或閾值(zhi)電(dian)(dian)壓(ya)(ya)，硅管(guan)(guan)(guan)(guan)(guan)約為(wei)(wei)0.5V，鍺(zang)管(guan)(guan)(guan)(guan)(guan)約為(wei)(wei)0.1V。硅二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)的(de)(de)正(zheng)(zheng)(zheng)(zheng)向導(dao)通(tong)(tong)壓(ya)(ya)降約為(wei)(wei)0.6~0.8V，鍺(zang)二(er)(er)極(ji)(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)(guan)(guan)的(de)(de)正(zheng)(zheng)(zheng)(zheng)向導(dao)通(tong)(tong)壓(ya)(ya)降約為(wei)(wei)0.2~0.3V。

反向性

外加反向電壓不超過一定范圍時，通過二極管的電流是少數載流子漂移運動所形成反向電流。由于反向電流很小，二極管處于截止狀態。這(zhe)個(ge)反(fan)(fan)向(xiang)(xiang)電(dian)流又稱為反(fan)(fan)向(xiang)(xiang)飽和電(dian)流或漏電(dian)流，二極管(guan)的(de)反(fan)(fan)向(xiang)(xiang)飽和電(dian)流受(shou)(shou)溫(wen)度影響很大。一般硅管(guan)的(de)反(fan)(fan)向(xiang)(xiang)電(dian)流比鍺(zang)管(guan)小得(de)多，小功率(lv)硅管(guan)的(de)反(fan)(fan)向(xiang)(xiang)飽和電(dian)流在nA數(shu)量級(ji)，小功率(lv)鍺(zang)管(guan)在μA數(shu)量級(ji)。溫(wen)度升高(gao)時，半導體受(shou)(shou)熱激發，少數(shu)載流子(zi)數(shu)目增加，反(fan)(fan)向(xiang)(xiang)飽和電(dian)流也隨之(zhi)增加。

反向擊穿

齊納擊穿

反向擊(ji)(ji)穿(chuan)按機理分為(wei)齊納(na)擊(ji)(ji)穿(chuan)和雪(xue)崩擊(ji)(ji)穿(chuan)兩種情況。在高摻雜濃度(du)(du)的情況下，因勢壘(lei)區(qu)寬(kuan)(kuan)度(du)(du)很小，反向電壓較大時，破壞了勢壘(lei)區(qu)內(nei)共價(jia)鍵(jian)結構，使價(jia)電子脫離(li)共價(jia)鍵(jian)束縛，產生電子-空穴對，致使電流急劇增(zeng)大，這種擊(ji)(ji)穿(chuan)稱為(wei)齊納(na)擊(ji)(ji)穿(chuan)。如果摻雜濃度(du)(du)較低，勢壘(lei)區(qu)寬(kuan)(kuan)度(du)(du)較寬(kuan)(kuan)，不容易產生齊納(na)擊(ji)(ji)穿(chuan)。

雪崩擊穿

另(ling)一種擊(ji)穿(chuan)為雪崩(beng)擊(ji)穿(chuan)。當反(fan)向電(dian)(dian)(dian)(dian)壓增加到較大數值時，外加電(dian)(dian)(dian)(dian)場(chang)使(shi)電(dian)(dian)(dian)(dian)子漂移速(su)(su)度加快，從而與共價(jia)(jia)鍵中(zhong)的價(jia)(jia)電(dian)(dian)(dian)(dian)子相碰(peng)撞，把價(jia)(jia)電(dian)(dian)(dian)(dian)子撞出共價(jia)(jia)鍵，產(chan)生新(xin)的電(dian)(dian)(dian)(dian)子-空穴(xue)對。新(xin)產(chan)生的電(dian)(dian)(dian)(dian)子-空穴(xue)被電(dian)(dian)(dian)(dian)場(chang)加速(su)(su)后又撞出其它價(jia)(jia)電(dian)(dian)(dian)(dian)子，載流子雪崩(beng)式地(di)增加，致使(shi)電(dian)(dian)(dian)(dian)流急(ji)劇(ju)增加，這種擊(ji)穿(chuan)稱為雪崩(beng)擊(ji)穿(chuan)。無論哪種擊(ji)穿(chuan)，若對其電(dian)(dian)(dian)(dian)流不(bu)加限(xian)制，都可能造成(cheng)PN結永久性損壞。