【二(er)極管的作用】二(er)極管在(zai)電路中有什么作用 二(er)極管的特性(xing)有哪些

二極管在電路中有什么作用

二極管是電子元件當(dang)中(zhong)一種具有兩個電極(ji)的裝置，只允(yun)許電流由單(dan)一方(fang)向(xiang)流過，許多(duo)的使用是(shi)應(ying)用其整流的功(gong)能。而(er)變容二極(ji)管則用來當(dang)作電子(zi)式的可調(diao)電容器。大(da)部(bu)分二極(ji)管所具備(bei)的電流方(fang)向(xiang)性我們通常(chang)稱之為“整流”功(gong)能。二極(ji)管最普遍的功(gong)能就是(shi)只允(yun)許電流由單(dan)一方(fang)向(xiang)通過（稱為順(shun)向(xiang)偏壓），反向(xiang)時阻斷 （稱為逆(ni)向(xiang)偏壓）。因此，二極(ji)管可以想成電子(zi)版(ban)的逆(ni)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(shi)壞的，反向(xiang)電阻如(ru)果(guo)很大(da)這就說明這個二極管是(shi)好的。

二極管的特性有哪些

正向性

外加正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)時，在(zai)正(zheng)(zheng)(zheng)向(xiang)特性的(de)起始部分，正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)很(hen)小，不足以克服PN結內(nei)(nei)電(dian)(dian)(dian)(dian)場的(de)阻擋(dang)作(zuo)用(yong)(yong)，正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)流(liu)幾乎為(wei)(wei)(wei)(wei)零，這(zhe)(zhe)一段稱(cheng)為(wei)(wei)(wei)(wei)死區。這(zhe)(zhe)個(ge)不能使二(er)極(ji)(ji)管(guan)(guan)導通(tong)的(de)正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)稱(cheng)為(wei)(wei)(wei)(wei)死區電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。當正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)大于死區電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)以后，PN結內(nei)(nei)電(dian)(dian)(dian)(dian)場被克服，二(er)極(ji)(ji)管(guan)(guan)正(zheng)(zheng)(zheng)向(xiang)導通(tong)，電(dian)(dian)(dian)(dian)流(liu)隨電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)增大而(er)迅(xun)速上升(sheng)。在(zai)正(zheng)(zheng)(zheng)常使用(yong)(yong)的(de)電(dian)(dian)(dian)(dian)流(liu)范圍內(nei)(nei)，導通(tong)時二(er)極(ji)(ji)管(guan)(guan)的(de)端(duan)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)幾乎維持不變，這(zhe)(zhe)個(ge)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)稱(cheng)為(wei)(wei)(wei)(wei)二(er)極(ji)(ji)管(guan)(guan)的(de)正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。當二(er)極(ji)(ji)管(guan)(guan)兩端(duan)的(de)正(zheng)(zheng)(zheng)向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)超(chao)過(guo)一定(ding)數值(zhi)，內(nei)(nei)電(dian)(dian)(dian)(dian)場很(hen)快被削弱，特性電(dian)(dian)(dian)(dian)流(liu)迅(xun)速增長，二(er)極(ji)(ji)管(guan)(guan)正(zheng)(zheng)(zheng)向(xiang)導通(tong)。叫(jiao)做門(men)坎電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)或(huo)閾值(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，硅管(guan)(guan)約(yue)(yue)為(wei)(wei)(wei)(wei)0.5V，鍺管(guan)(guan)約(yue)(yue)為(wei)(wei)(wei)(wei)0.1V。硅二(er)極(ji)(ji)管(guan)(guan)的(de)正(zheng)(zheng)(zheng)向(xiang)導通(tong)壓(ya)(ya)(ya)(ya)(ya)降約(yue)(yue)為(wei)(wei)(wei)(wei)0.6~0.8V，鍺二(er)極(ji)(ji)管(guan)(guan)的(de)正(zheng)(zheng)(zheng)向(xiang)導通(tong)壓(ya)(ya)(ya)(ya)(ya)降約(yue)(yue)為(wei)(wei)(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。這個反(fan)(fan)向(xiang)(xiang)電(dian)(dian)流(liu)又稱為反(fan)(fan)向(xiang)(xiang)飽(bao)和(he)電(dian)(dian)流(liu)或漏電(dian)(dian)流(liu)，二極(ji)管(guan)的反(fan)(fan)向(xiang)(xiang)飽(bao)和(he)電(dian)(dian)流(liu)受溫(wen)度(du)影響很(hen)大。一般硅(gui)管(guan)的反(fan)(fan)向(xiang)(xiang)電(dian)(dian)流(liu)比鍺管(guan)小(xiao)得(de)多，小(xiao)功(gong)率硅(gui)管(guan)的反(fan)(fan)向(xiang)(xiang)飽(bao)和(he)電(dian)(dian)流(liu)在nA數量級，小(xiao)功(gong)率鍺管(guan)在μA數量級。溫(wen)度(du)升高時，半導(dao)體(ti)受熱激發，少數載(zai)流(liu)子(zi)數目增加(jia)，反(fan)(fan)向(xiang)(xiang)飽(bao)和(he)電(dian)(dian)流(liu)也隨之(zhi)增加(jia)。

反向擊穿

齊納擊穿

反向擊穿(chuan)按機理(li)分為(wei)齊(qi)納(na)(na)擊穿(chuan)和(he)雪(xue)崩擊穿(chuan)兩種情況。在高摻雜濃度(du)的情況下，因勢(shi)壘(lei)區寬度(du)很小(xiao)，反向電壓較(jiao)大時，破壞了勢(shi)壘(lei)區內(nei)共價(jia)(jia)鍵(jian)(jian)結構，使價(jia)(jia)電子(zi)脫離共價(jia)(jia)鍵(jian)(jian)束縛(fu)，產生(sheng)電子(zi)-空穴對，致使電流急(ji)劇增大，這種擊穿(chuan)稱為(wei)齊(qi)納(na)(na)擊穿(chuan)。如果摻雜濃度(du)較(jiao)低，勢(shi)壘(lei)區寬度(du)較(jiao)寬，不容易產生(sheng)齊(qi)納(na)(na)擊穿(chuan)。

雪崩擊穿

另一(yi)種擊(ji)穿為雪崩(beng)擊(ji)穿。當反向電(dian)(dian)(dian)壓增(zeng)(zeng)加(jia)到(dao)較大數值時(shi)，外(wai)加(jia)電(dian)(dian)(dian)場使電(dian)(dian)(dian)子(zi)漂移(yi)速(su)度加(jia)快，從而與(yu)共(gong)價(jia)鍵中的(de)價(jia)電(dian)(dian)(dian)子(zi)相碰撞(zhuang)，把價(jia)電(dian)(dian)(dian)子(zi)撞(zhuang)出共(gong)價(jia)鍵，產(chan)(chan)生新(xin)的(de)電(dian)(dian)(dian)子(zi)-空(kong)穴(xue)對。新(xin)產(chan)(chan)生的(de)電(dian)(dian)(dian)子(zi)-空(kong)穴(xue)被電(dian)(dian)(dian)場加(jia)速(su)后又(you)撞(zhuang)出其它(ta)價(jia)電(dian)(dian)(dian)子(zi)，載流子(zi)雪崩(beng)式地增(zeng)(zeng)加(jia)，致(zhi)使電(dian)(dian)(dian)流急劇增(zeng)(zeng)加(jia)，這(zhe)種擊(ji)穿稱為雪崩(beng)擊(ji)穿。無論哪種擊(ji)穿，若對其電(dian)(dian)(dian)流不(bu)加(jia)限制，都可能造成(cheng)PN結永久性(xing)損(sun)壞。