光電二極管原理
普通二(er)極(ji)(ji)管在反(fan)向電(dian)(dian)(dian)壓作用時(shi)(shi)處于截止狀(zhuang)態，只能流(liu)(liu)(liu)(liu)過微弱的(de)反(fan)向電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，光(guang)(guang)電(dian)(dian)(dian)二(er)極(ji)(ji)管在設計和制作時(shi)(shi)盡量(liang)使PN結的(de)面積相(xiang)對(dui)較大(da)，以便接收入射光(guang)(guang)。光(guang)(guang)電(dian)(dian)(dian)二(er)極(ji)(ji)管是在反(fan)向電(dian)(dian)(dian)壓作用下工(gong)作的(de)，沒有光(guang)(guang)照時(shi)(shi)，反(fan)向電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)極(ji)(ji)其(qi)微弱，叫暗電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)；有光(guang)(guang)照時(shi)(shi)，反(fan)向電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)迅(xun)速增大(da)到幾十微安，稱(cheng)為光(guang)(guang)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。光(guang)(guang)的(de)強度越大(da)，反(fan)向電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)也越大(da)。光(guang)(guang)的(de)變化(hua)引起光(guang)(guang)電(dian)(dian)(dian)二(er)極(ji)(ji)管電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)變化(hua)，這就可以把光(guang)(guang)信號轉換(huan)成電(dian)(dian)(dian)信號，成為光(guang)(guang)電(dian)(dian)(dian)傳感器件。
光電二極管的工作原理
光電(dian)(dian)(dian)二極(ji)管(guan)是將光信號(hao)轉換成(cheng)電(dian)(dian)(dian)流或電(dian)(dian)(dian)壓信號(hao)的特殊二極(ji)管(guan)，它與常(chang)規二極(ji)管(guan)結構(gou)上基本(ben)相(xiang)似，都具有一個(ge)PN結，但(dan)光電(dian)(dian)(dian)二極(ji)管(guan)在設計(ji)和制作(zuo)時盡量使PN結的面積(ji)相(xiang)對較大，以(yi)便接收入射光。
其基本原理是(shi)(shi)當光(guang)(guang)照(zhao)在(zai)(zai)(zai)二極(ji)管上時(shi)，被吸收的(de)(de)(de)光(guang)(guang)能(neng)轉換成電(dian)(dian)(dian)(dian)能(neng)。光(guang)(guang)電(dian)(dian)(dian)(dian)二極(ji)管工作(zuo)(zuo)在(zai)(zai)(zai)反(fan)向電(dian)(dian)(dian)(dian)壓作(zuo)(zuo)用(yong)下(xia)，只通過(guo)微(wei)弱的(de)(de)(de)電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)（一(yi)般小(xiao)于0.1微(wei)安），稱為暗電(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，有光(guang)(guang)照(zhao)時(shi)，攜帶(dai)能(neng)量的(de)(de)(de)光(guang)(guang)子(zi)(zi)(zi)(zi)(zi)進(jin)入PN結(jie)(jie)(jie)(jie)后，把能(neng)量傳給共價(jia)鍵上的(de)(de)(de)電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)，使有些電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)掙脫共價(jia)鍵，而(er)產生電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)-空(kong)穴對，稱為光(guang)(guang)生載(zai)流(liu)(liu)(liu)子(zi)(zi)(zi)(zi)(zi)，因為光(guang)(guang)生載(zai)流(liu)(liu)(liu)子(zi)(zi)(zi)(zi)(zi)的(de)(de)(de)數(shu)目(mu)是(shi)(shi)有限的(de)(de)(de)，而(er)光(guang)(guang)照(zhao)前多子(zi)(zi)(zi)(zi)(zi)的(de)(de)(de)數(shu)目(mu)遠大于光(guang)(guang)生載(zai)流(liu)(liu)(liu)子(zi)(zi)(zi)(zi)(zi)的(de)(de)(de)數(shu)目(mu)，所以光(guang)(guang)生載(zai)流(liu)(liu)(liu)子(zi)(zi)(zi)(zi)(zi)對多子(zi)(zi)(zi)(zi)(zi)的(de)(de)(de)影響是(shi)(shi)很小(xiao)的(de)(de)(de)，但少(shao)子(zi)(zi)(zi)(zi)(zi)的(de)(de)(de)數(shu)目(mu)少(shao)有比較大的(de)(de)(de)影響，這就是(shi)(shi)為什么光(guang)(guang)電(dian)(dian)(dian)(dian)二極(ji)管是(shi)(shi)工作(zuo)(zuo)在(zai)(zai)(zai)反(fan)向電(dian)(dian)(dian)(dian)壓下(xia)而(er)不是(shi)(shi)正(zheng)向電(dian)(dian)(dian)(dian)壓下(xia)，于是(shi)(shi)在(zai)(zai)(zai)反(fan)向電(dian)(dian)(dian)(dian)壓作(zuo)(zuo)用(yong)下(xia)被光(guang)(guang)生載(zai)流(liu)(liu)(liu)子(zi)(zi)(zi)(zi)(zi)影響而(er)增加(jia)的(de)(de)(de)少(shao)子(zi)(zi)(zi)(zi)(zi)參加(jia)漂流(liu)(liu)(liu)運動，在(zai)(zai)(zai)P區，光(guang)(guang)生電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)擴(kuo)散到PN結(jie)(jie)(jie)(jie)，如果(guo)P區厚(hou)度小(xiao)于電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)擴(kuo)散長度，那么大部分光(guang)(guang)生電(dian)(dian)(dian)(dian)子(zi)(zi)(zi)(zi)(zi)將能(neng)穿(chuan)過(guo)P區到達PN結(jie)(jie)(jie)(jie)，在(zai)(zai)(zai)N區也是(shi)(shi)相(xiang)同的(de)(de)(de)道理，也因此光(guang)(guang)電(dian)(dian)(dian)(dian)二極(ji)管在(zai)(zai)(zai)制(zhi)作(zuo)(zuo)時(shi)，PN結(jie)(jie)(jie)(jie)的(de)(de)(de)結(jie)(jie)(jie)(jie)深(shen)很淺，以促使少(shao)子(zi)(zi)(zi)(zi)(zi)的(de)(de)(de)漂移。
綜(zong)上(shang)若光(guang)(guang)的(de)(de)強度越大(da)，反向(xiang)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)也就(jiu)越大(da)，這種特性稱為光(guang)(guang)導電(dian)(dian)(dian)，而這種現象引起的(de)(de)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)稱為光(guang)(guang)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。總的(de)(de)來說光(guang)(guang)電(dian)(dian)(dian)二(er)極管的(de)(de)工作是一(yi)個(ge)吸收的(de)(de)過程(cheng)，它(ta)將光(guang)(guang)的(de)(de)變化轉(zhuan)換成反向(xiang)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的(de)(de)變化，光(guang)(guang)照產生電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)和暗(an)(an)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的(de)(de)綜(zong)合(he)就(jiu)是光(guang)(guang)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，因此(ci)光(guang)(guang)電(dian)(dian)(dian)二(er)極管的(de)(de)暗(an)(an)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)因盡量最小(xiao)化來提(ti)器件對光(guang)(guang)的(de)(de)靈(ling)敏度，光(guang)(guang)的(de)(de)強度與光(guang)(guang)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)成正比，因而就(jiu)可以把光(guang)(guang)信號轉(zhuan)換成電(dian)(dian)(dian)信號。
PIN光電二極管
光(guang)電(dian)二(er)極(ji)管的(de)(de)PN結(jie)中間摻(chan)入(ru)(ru)一(yi)(yi)層(ceng)(ceng)濃(nong)度(du)很(hen)低(di)的(de)(de)N型(xing)半導體，就可以增大耗(hao)(hao)盡區(qu)的(de)(de)寬度(du)，達到減(jian)小擴散(san)運動的(de)(de)影響，提(ti)高響應速度(du)的(de)(de)目(mu)的(de)(de)。由(you)于這一(yi)(yi)摻(chan)入(ru)(ru)層(ceng)(ceng)的(de)(de)摻(chan)雜濃(nong)度(du)低(di)，近乎本征（Intrinsic）半導體，故(gu)稱(cheng)I層(ceng)(ceng)，因(yin)此這種結(jie)構成為PIN光(guang)電(dian)二(er)極(ji)管。I層(ceng)(ceng)較厚，幾(ji)乎占(zhan)據了(le)整個耗(hao)(hao)盡區(qu)。絕大部分的(de)(de)入(ru)(ru)射(she)(she)光(guang)在I層(ceng)(ceng)內被(bei)吸(xi)收并產生大量的(de)(de)電(dian)子-空穴對。在I層(ceng)(ceng)兩(liang)側是摻(chan)雜濃(nong)度(du)很(hen)高的(de)(de)P型(xing)和N型(xing)半導體，P層(ceng)(ceng)和N層(ceng)(ceng)很(hen)薄，吸(xi)收入(ru)(ru)射(she)(she)光(guang)的(de)(de)比例很(hen)小。
（來源：網(wang)站，版權(quan)歸原作(zuo)者）
