【二(er)極(ji)管的作用(yong)】二(er)極(ji)管在電路中有什么作用(yong) 二(er)極(ji)管的特性有哪(na)些

二極管在電路中有什么作用

二極管是電子元件當中一種具有(you)兩個電(dian)極(ji)的(de)(de)(de)裝置，只(zhi)(zhi)允許電(dian)流(liu)(liu)由單(dan)一方向(xiang)(xiang)流(liu)(liu)過，許多的(de)(de)(de)使用(yong)是應用(yong)其整(zheng)流(liu)(liu)的(de)(de)(de)功能(neng)。而變容二極(ji)管(guan)(guan)則用(yong)來當作(zuo)電(dian)子式的(de)(de)(de)可調電(dian)容器。大(da)部分(fen)二極(ji)管(guan)(guan)所具備的(de)(de)(de)電(dian)流(liu)(liu)方向(xiang)(xiang)性(xing)我們(men)通(tong)(tong)常稱(cheng)之為“整(zheng)流(liu)(liu)”功能(neng)。二極(ji)管(guan)(guan)最普遍的(de)(de)(de)功能(neng)就是只(zhi)(zhi)允許電(dian)流(liu)(liu)由單(dan)一方向(xiang)(xiang)通(tong)(tong)過（稱(cheng)為順向(xiang)(xiang)偏壓(ya)(ya)），反向(xiang)(xiang)時阻斷 （稱(cheng)為逆向(xiang)(xiang)偏壓(ya)(ya)）。因此，二極(ji)管(guan)(guan)可以想成電(dian)子版的(de)(de)(de)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(huai)的(de)，反向(xiang)電阻如果很大這就說明這個(ge)二極管是好(hao)的(de)。

二極管的特性有哪些

正向性

外加正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)時(shi)，在正(zheng)(zheng)向(xiang)(xiang)(xiang)特性的(de)(de)起(qi)始(shi)部分，正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)很(hen)小，不足(zu)以克服PN結(jie)內(nei)(nei)電(dian)(dian)(dian)場的(de)(de)阻(zu)擋作用，正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)流(liu)幾乎為零，這一段稱(cheng)為死區(qu)(qu)。這個(ge)不能使二極(ji)(ji)管(guan)(guan)導通(tong)(tong)的(de)(de)正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)稱(cheng)為死區(qu)(qu)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)。當(dang)正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)大于(yu)死區(qu)(qu)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)以后，PN結(jie)內(nei)(nei)電(dian)(dian)(dian)場被克服，二極(ji)(ji)管(guan)(guan)正(zheng)(zheng)向(xiang)(xiang)(xiang)導通(tong)(tong)，電(dian)(dian)(dian)流(liu)隨(sui)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)增(zeng)大而(er)迅速(su)上升。在正(zheng)(zheng)常使用的(de)(de)電(dian)(dian)(dian)流(liu)范圍內(nei)(nei)，導通(tong)(tong)時(shi)二極(ji)(ji)管(guan)(guan)的(de)(de)端(duan)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)幾乎維持不變，這個(ge)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)稱(cheng)為二極(ji)(ji)管(guan)(guan)的(de)(de)正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)。當(dang)二極(ji)(ji)管(guan)(guan)兩端(duan)的(de)(de)正(zheng)(zheng)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)超過(guo)一定數值(zhi)，內(nei)(nei)電(dian)(dian)(dian)場很(hen)快被削(xue)弱，特性電(dian)(dian)(dian)流(liu)迅速(su)增(zeng)長，二極(ji)(ji)管(guan)(guan)正(zheng)(zheng)向(xiang)(xiang)(xiang)導通(tong)(tong)。叫(jiao)做門坎電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)或閾值(zhi)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，硅管(guan)(guan)約為0.5V，鍺管(guan)(guan)約為0.1V。硅二極(ji)(ji)管(guan)(guan)的(de)(de)正(zheng)(zheng)向(xiang)(xiang)(xiang)導通(tong)(tong)壓(ya)(ya)(ya)(ya)降約為0.6~0.8V，鍺二極(ji)(ji)管(guan)(guan)的(de)(de)正(zheng)(zheng)向(xiang)(xiang)(xiang)導通(tong)(tong)壓(ya)(ya)(ya)(ya)降約為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。這個反(fan)向(xiang)電(dian)(dian)流又稱為反(fan)向(xiang)飽(bao)(bao)和電(dian)(dian)流或漏電(dian)(dian)流，二極管(guan)的反(fan)向(xiang)飽(bao)(bao)和電(dian)(dian)流受溫度影響(xiang)很大。一般硅管(guan)的反(fan)向(xiang)電(dian)(dian)流比(bi)鍺(zang)管(guan)小(xiao)得多，小(xiao)功(gong)(gong)率硅管(guan)的反(fan)向(xiang)飽(bao)(bao)和電(dian)(dian)流在nA數(shu)(shu)量級，小(xiao)功(gong)(gong)率鍺(zang)管(guan)在μA數(shu)(shu)量級。溫度升高時(shi)，半導(dao)體受熱(re)激發，少數(shu)(shu)載流子(zi)數(shu)(shu)目增(zeng)加，反(fan)向(xiang)飽(bao)(bao)和電(dian)(dian)流也隨(sui)之增(zeng)加。

反向擊穿

齊納擊穿

反(fan)向(xiang)擊穿(chuan)按機(ji)理(li)分為齊納(na)擊穿(chuan)和雪崩(beng)擊穿(chuan)兩種情況。在高摻雜濃(nong)(nong)度(du)(du)的情況下，因勢壘區(qu)寬度(du)(du)很(hen)小，反(fan)向(xiang)電壓較(jiao)大時，破壞了勢壘區(qu)內共(gong)價(jia)鍵(jian)結構(gou)，使(shi)價(jia)電子脫離共(gong)價(jia)鍵(jian)束縛，產生電子-空穴對，致使(shi)電流急劇增大，這種擊穿(chuan)稱為齊納(na)擊穿(chuan)。如果(guo)摻雜濃(nong)(nong)度(du)(du)較(jiao)低，勢壘區(qu)寬度(du)(du)較(jiao)寬，不容易產生齊納(na)擊穿(chuan)。

雪崩擊穿

另一種擊穿(chuan)(chuan)(chuan)為(wei)雪(xue)崩擊穿(chuan)(chuan)(chuan)。當(dang)反向電(dian)壓增(zeng)(zeng)加(jia)(jia)到較大數(shu)值時，外加(jia)(jia)電(dian)場使(shi)電(dian)子(zi)(zi)漂移(yi)速度加(jia)(jia)快，從而與共價鍵(jian)中的(de)(de)價電(dian)子(zi)(zi)相碰撞，把(ba)價電(dian)子(zi)(zi)撞出共價鍵(jian)，產(chan)生新(xin)的(de)(de)電(dian)子(zi)(zi)-空(kong)穴對。新(xin)產(chan)生的(de)(de)電(dian)子(zi)(zi)-空(kong)穴被(bei)電(dian)場加(jia)(jia)速后又(you)撞出其(qi)它價電(dian)子(zi)(zi)，載(zai)流子(zi)(zi)雪(xue)崩式地增(zeng)(zeng)加(jia)(jia)，致使(shi)電(dian)流急(ji)劇增(zeng)(zeng)加(jia)(jia)，這(zhe)種擊穿(chuan)(chuan)(chuan)稱為(wei)雪(xue)崩擊穿(chuan)(chuan)(chuan)。無論哪種擊穿(chuan)(chuan)(chuan)，若對其(qi)電(dian)流不加(jia)(jia)限制(zhi)，都可(ke)能造成PN結(jie)永久性損壞。