光電二極管原理

普通二(er)極管(guan)(guan)在(zai)(zai)反(fan)向(xiang)電(dian)(dian)(dian)(dian)(dian)壓作(zuo)(zuo)(zuo)用時處(chu)于截止狀(zhuang)態，只能流(liu)過微弱(ruo)的(de)(de)反(fan)向(xiang)電(dian)(dian)(dian)(dian)(dian)流(liu)，光(guang)(guang)(guang)電(dian)(dian)(dian)(dian)(dian)二(er)極管(guan)(guan)在(zai)(zai)設計(ji)和制作(zuo)(zuo)(zuo)時盡量(liang)使(shi)PN結的(de)(de)面(mian)積(ji)相對較大(da)(da)，以(yi)便接收(shou)入射(she)光(guang)(guang)(guang)。光(guang)(guang)(guang)電(dian)(dian)(dian)(dian)(dian)二(er)極管(guan)(guan)是在(zai)(zai)反(fan)向(xiang)電(dian)(dian)(dian)(dian)(dian)壓作(zuo)(zuo)(zuo)用下工作(zuo)(zuo)(zuo)的(de)(de)，沒有(you)光(guang)(guang)(guang)照時，反(fan)向(xiang)電(dian)(dian)(dian)(dian)(dian)流(liu)極其微弱(ruo)，叫(jiao)暗電(dian)(dian)(dian)(dian)(dian)流(liu)；有(you)光(guang)(guang)(guang)照時，反(fan)向(xiang)電(dian)(dian)(dian)(dian)(dian)流(liu)迅(xun)速增大(da)(da)到(dao)幾十微安(an)，稱為(wei)光(guang)(guang)(guang)電(dian)(dian)(dian)(dian)(dian)流(liu)。光(guang)(guang)(guang)的(de)(de)強(qiang)度越(yue)大(da)(da)，反(fan)向(xiang)電(dian)(dian)(dian)(dian)(dian)流(liu)也越(yue)大(da)(da)。光(guang)(guang)(guang)的(de)(de)變化引起(qi)光(guang)(guang)(guang)電(dian)(dian)(dian)(dian)(dian)二(er)極管(guan)(guan)電(dian)(dian)(dian)(dian)(dian)流(liu)變化，這就可(ke)以(yi)把光(guang)(guang)(guang)信(xin)號轉換成電(dian)(dian)(dian)(dian)(dian)信(xin)號，成為(wei)光(guang)(guang)(guang)電(dian)(dian)(dian)(dian)(dian)傳感器件。

光電二極管的工作原理

光電二(er)極(ji)管是(shi)將光信號(hao)(hao)轉換成(cheng)電流或電壓信號(hao)(hao)的特殊二(er)極(ji)管，它與常規(gui)二(er)極(ji)管結(jie)構上基本相似，都具有一個PN結(jie)，但光電二(er)極(ji)管在設計和(he)制作時盡量(liang)使(shi)PN結(jie)的面積相對(dui)較大，以便接收入射光。

其基(ji)本原理是當光(guang)照(zhao)在(zai)(zai)(zai)(zai)二極管(guan)上時，被(bei)吸收(shou)的(de)(de)光(guang)能(neng)轉換成電(dian)(dian)(dian)(dian)能(neng)。光(guang)電(dian)(dian)(dian)(dian)二極管(guan)工作(zuo)(zuo)在(zai)(zai)(zai)(zai)反向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)作(zuo)(zuo)用下，只通過微(wei)弱的(de)(de)電(dian)(dian)(dian)(dian)流(liu)(liu)（一(yi)般(ban)小于0.1微(wei)安），稱為(wei)暗電(dian)(dian)(dian)(dian)流(liu)(liu)，有(you)(you)(you)光(guang)照(zhao)時，攜帶能(neng)量(liang)的(de)(de)光(guang)子(zi)(zi)(zi)(zi)進入PN結后，把能(neng)量(liang)傳給(gei)共價(jia)鍵上的(de)(de)電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)，使(shi)有(you)(you)(you)些電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)掙脫共價(jia)鍵，而(er)產(chan)生電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)-空穴對(dui)，稱為(wei)光(guang)生載流(liu)(liu)子(zi)(zi)(zi)(zi)，因(yin)為(wei)光(guang)生載流(liu)(liu)子(zi)(zi)(zi)(zi)的(de)(de)數(shu)(shu)目是有(you)(you)(you)限(xian)的(de)(de)，而(er)光(guang)照(zhao)前多(duo)子(zi)(zi)(zi)(zi)的(de)(de)數(shu)(shu)目遠大于光(guang)生載流(liu)(liu)子(zi)(zi)(zi)(zi)的(de)(de)數(shu)(shu)目，所以光(guang)生載流(liu)(liu)子(zi)(zi)(zi)(zi)對(dui)多(duo)子(zi)(zi)(zi)(zi)的(de)(de)影(ying)(ying)響(xiang)是很小的(de)(de)，但少子(zi)(zi)(zi)(zi)的(de)(de)數(shu)(shu)目少有(you)(you)(you)比較(jiao)大的(de)(de)影(ying)(ying)響(xiang)，這就是為(wei)什(shen)么光(guang)電(dian)(dian)(dian)(dian)二極管(guan)是工作(zuo)(zuo)在(zai)(zai)(zai)(zai)反向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)下而(er)不(bu)是正向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)下，于是在(zai)(zai)(zai)(zai)反向(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)作(zuo)(zuo)用下被(bei)光(guang)生載流(liu)(liu)子(zi)(zi)(zi)(zi)影(ying)(ying)響(xiang)而(er)增加的(de)(de)少子(zi)(zi)(zi)(zi)參加漂(piao)流(liu)(liu)運動，在(zai)(zai)(zai)(zai)P區，光(guang)生電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)擴散到PN結，如果P區厚度(du)(du)小于電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)擴散長(chang)度(du)(du)，那么大部分(fen)光(guang)生電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)將能(neng)穿(chuan)過P區到達(da)PN結，在(zai)(zai)(zai)(zai)N區也是相同的(de)(de)道理，也因(yin)此光(guang)電(dian)(dian)(dian)(dian)二極管(guan)在(zai)(zai)(zai)(zai)制作(zuo)(zuo)時，PN結的(de)(de)結深很淺，以促使(shi)少子(zi)(zi)(zi)(zi)的(de)(de)漂(piao)移。

綜上若光(guang)(guang)的(de)(de)強度越大，反(fan)向電(dian)(dian)流(liu)(liu)也就越大，這(zhe)種特性稱為光(guang)(guang)導電(dian)(dian)，而這(zhe)種現象(xiang)引起的(de)(de)電(dian)(dian)流(liu)(liu)稱為光(guang)(guang)電(dian)(dian)流(liu)(liu)。總(zong)的(de)(de)來說光(guang)(guang)電(dian)(dian)二極管的(de)(de)工(gong)作是(shi)一個吸收的(de)(de)過程，它將光(guang)(guang)的(de)(de)變化(hua)轉換成反(fan)向電(dian)(dian)流(liu)(liu)的(de)(de)變化(hua)，光(guang)(guang)照(zhao)產生電(dian)(dian)流(liu)(liu)和暗(an)電(dian)(dian)流(liu)(liu)的(de)(de)綜合就是(shi)光(guang)(guang)電(dian)(dian)流(liu)(liu)，因(yin)此光(guang)(guang)電(dian)(dian)二極管的(de)(de)暗(an)電(dian)(dian)流(liu)(liu)因(yin)盡(jin)量最小化(hua)來提器(qi)件對光(guang)(guang)的(de)(de)靈敏(min)度，光(guang)(guang)的(de)(de)強度與(yu)光(guang)(guang)電(dian)(dian)流(liu)(liu)成正比，因(yin)而就可(ke)以把光(guang)(guang)信(xin)號轉換成電(dian)(dian)信(xin)號。

PIN光電二極管

光(guang)電(dian)二極(ji)管的(de)(de)PN結(jie)中(zhong)間(jian)摻(chan)(chan)入一層(ceng)(ceng)(ceng)濃(nong)度(du)很(hen)低的(de)(de)N型半導(dao)體，就可以增大(da)耗盡(jin)區的(de)(de)寬(kuan)度(du)，達到(dao)減(jian)小擴(kuo)散運動的(de)(de)影響，提高響應(ying)速度(du)的(de)(de)目的(de)(de)。由于這一摻(chan)(chan)入層(ceng)(ceng)(ceng)的(de)(de)摻(chan)(chan)雜(za)濃(nong)度(du)低，近(jin)乎本征（Intrinsic）半導(dao)體，故稱I層(ceng)(ceng)(ceng)，因此這種結(jie)構(gou)成為PIN光(guang)電(dian)二極(ji)管。I層(ceng)(ceng)(ceng)較(jiao)厚，幾(ji)乎占據了整個耗盡(jin)區。絕大(da)部分的(de)(de)入射光(guang)在I層(ceng)(ceng)(ceng)內被吸收并產生大(da)量的(de)(de)電(dian)子-空穴(xue)對(dui)。在I層(ceng)(ceng)(ceng)兩側是摻(chan)(chan)雜(za)濃(nong)度(du)很(hen)高的(de)(de)P型和(he)(he)N型半導(dao)體，P層(ceng)(ceng)(ceng)和(he)(he)N層(ceng)(ceng)(ceng)很(hen)薄，吸收入射光(guang)的(de)(de)比(bi)例很(hen)小。

（來源：網站(zhan)，版權歸原作者(zhe)）