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

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)極的(de)(de)(de)(de)裝置，只(zhi)允許電(dian)流(liu)由單一(yi)方(fang)向流(liu)過，許多的(de)(de)(de)(de)使用(yong)是(shi)應用(yong)其整流(liu)的(de)(de)(de)(de)功(gong)能(neng)(neng)。而變容(rong)二(er)極管則用(yong)來當作電(dian)子(zi)式的(de)(de)(de)(de)可(ke)調電(dian)容(rong)器。大(da)部分二(er)極管所具備(bei)的(de)(de)(de)(de)電(dian)流(liu)方(fang)向性我們通(tong)常稱之為“整流(liu)”功(gong)能(neng)(neng)。二(er)極管最普遍(bian)的(de)(de)(de)(de)功(gong)能(neng)(neng)就(jiu)是(shi)只(zhi)允許電(dian)流(liu)由單一(yi)方(fang)向通(tong)過（稱為順向偏壓），反向時阻斷 （稱為逆(ni)向偏壓）。因此，二(er)極管可(ke)以想成(cheng)電(dian)子(zi)版的(de)(de)(de)(de)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壞的，反向(xiang)電阻如果很大這就說明這個二極管是好的。

二極管的特性有哪些

正向性

外加正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)時，在(zai)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)特(te)性的(de)(de)(de)起(qi)始部分，正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)很小，不足以(yi)克服(fu)PN結(jie)內電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場(chang)的(de)(de)(de)阻擋作用(yong)，正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流幾乎為(wei)(wei)零，這(zhe)一段(duan)稱為(wei)(wei)死區。這(zhe)個(ge)不能(neng)使(shi)二(er)極(ji)管(guan)(guan)導通(tong)(tong)的(de)(de)(de)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)稱為(wei)(wei)死區電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。當(dang)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)大于(yu)死區電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)以(yi)后，PN結(jie)內電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場(chang)被(bei)克服(fu)，二(er)極(ji)管(guan)(guan)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)導通(tong)(tong)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流隨電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)增大而迅速上升(sheng)。在(zai)正(zheng)(zheng)(zheng)(zheng)常使(shi)用(yong)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流范圍內，導通(tong)(tong)時二(er)極(ji)管(guan)(guan)的(de)(de)(de)端電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)幾乎維持不變(bian)，這(zhe)個(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)稱為(wei)(wei)二(er)極(ji)管(guan)(guan)的(de)(de)(de)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。當(dang)二(er)極(ji)管(guan)(guan)兩端的(de)(de)(de)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)超過一定數值，內電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場(chang)很快(kuai)被(bei)削弱(ruo)，特(te)性電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流迅速增長，二(er)極(ji)管(guan)(guan)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)導通(tong)(tong)。叫做門坎電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)或(huo)閾值電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，硅管(guan)(guan)約(yue)(yue)為(wei)(wei)0.5V，鍺管(guan)(guan)約(yue)(yue)為(wei)(wei)0.1V。硅二(er)極(ji)管(guan)(guan)的(de)(de)(de)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)導通(tong)(tong)壓(ya)(ya)(ya)(ya)(ya)降約(yue)(yue)為(wei)(wei)0.6~0.8V，鍺二(er)極(ji)管(guan)(guan)的(de)(de)(de)正(zheng)(zheng)(zheng)(zheng)向(xiang)(xiang)(xiang)(xiang)(xiang)導通(tong)(tong)壓(ya)(ya)(ya)(ya)(ya)降約(yue)(yue)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)個反(fan)向(xiang)電(dian)流(liu)又稱(cheng)為反(fan)向(xiang)飽(bao)(bao)和(he)電(dian)流(liu)或漏電(dian)流(liu)，二極(ji)管的反(fan)向(xiang)飽(bao)(bao)和(he)電(dian)流(liu)受溫(wen)度影響很大(da)。一般硅(gui)管的反(fan)向(xiang)電(dian)流(liu)比(bi)鍺(zang)管小(xiao)(xiao)(xiao)得多(duo)，小(xiao)(xiao)(xiao)功(gong)率硅(gui)管的反(fan)向(xiang)飽(bao)(bao)和(he)電(dian)流(liu)在nA數(shu)量級，小(xiao)(xiao)(xiao)功(gong)率鍺(zang)管在μA數(shu)量級。溫(wen)度升高時(shi)，半導體受熱激發，少數(shu)載流(liu)子數(shu)目增(zeng)加，反(fan)向(xiang)飽(bao)(bao)和(he)電(dian)流(liu)也隨之增(zeng)加。

反向擊穿

齊納擊穿

反向(xiang)擊穿按機(ji)理分為齊納擊穿和雪崩擊穿兩種情況。在(zai)高(gao)摻雜濃度(du)(du)(du)的情況下，因(yin)勢(shi)壘區(qu)寬度(du)(du)(du)很(hen)小，反向(xiang)電壓較(jiao)大時，破壞(huai)了(le)勢(shi)壘區(qu)內共價(jia)(jia)鍵結構(gou)，使價(jia)(jia)電子(zi)(zi)脫(tuo)離共價(jia)(jia)鍵束縛(fu)，產生電子(zi)(zi)-空(kong)穴對，致使電流急劇(ju)增大，這(zhe)種擊穿稱為齊納擊穿。如果(guo)摻雜濃度(du)(du)(du)較(jiao)低，勢(shi)壘區(qu)寬度(du)(du)(du)較(jiao)寬，不容(rong)易產生齊納擊穿。

雪崩擊穿

另(ling)一種(zhong)擊穿(chuan)(chuan)為雪(xue)崩擊穿(chuan)(chuan)。當反向電(dian)(dian)壓增加(jia)(jia)到較(jiao)大數值時(shi)，外加(jia)(jia)電(dian)(dian)場(chang)使(shi)電(dian)(dian)子漂移(yi)速度加(jia)(jia)快(kuai)，從(cong)而與(yu)共價(jia)鍵(jian)(jian)中的價(jia)電(dian)(dian)子相碰撞(zhuang)，把價(jia)電(dian)(dian)子撞(zhuang)出(chu)共價(jia)鍵(jian)(jian)，產生(sheng)新的電(dian)(dian)子-空穴對(dui)。新產生(sheng)的電(dian)(dian)子-空穴被電(dian)(dian)場(chang)加(jia)(jia)速后(hou)又撞(zhuang)出(chu)其(qi)它價(jia)電(dian)(dian)子，載流子雪(xue)崩式地增加(jia)(jia)，致使(shi)電(dian)(dian)流急(ji)劇增加(jia)(jia)，這種(zhong)擊穿(chuan)(chuan)稱為雪(xue)崩擊穿(chuan)(chuan)。無論(lun)哪(na)種(zhong)擊穿(chuan)(chuan)，若對(dui)其(qi)電(dian)(dian)流不加(jia)(jia)限制，都可(ke)能造成PN結永久性損壞。