1、正(zheng)(zheng)向(xiang)(xiang)性:外加(jia)正(zheng)(zheng)向(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)壓(ya)時(shi),在正(zheng)(zheng)向(xiang)(xiang)特性的起始部(bu)分,正(zheng)(zheng)向(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)壓(ya)很小(xiao),不(bu)足以克(ke)服PN結內電(dian)(dian)(dian)(dian)(dian)場(chang)的阻擋作用,正(zheng)(zheng)向(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)流(liu)幾乎為(wei)零,這一(yi)段稱為(wei)死(si)區。這個不(bu)能使(shi)(shi)二級管導(dao)(dao)通的正(zheng)(zheng)向(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)壓(ya)稱為(wei)死(si)區電(dian)(dian)(dian)(dian)(dian)壓(ya)。當正(zheng)(zheng)向(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)壓(ya)大于死(si)區電(dian)(dian)(dian)(dian)(dian)壓(ya)以后,PN結內電(dian)(dian)(dian)(dian)(dian)場(chang)被克(ke)服,二級管正(zheng)(zheng)向(xiang)(xiang)導(dao)(dao)通,電(dian)(dian)(dian)(dian)(dian)流(liu)隨電(dian)(dian)(dian)(dian)(dian)壓(ya)增大而迅速上升。在正(zheng)(zheng)常使(shi)(shi)用的電(dian)(dian)(dian)(dian)(dian)流(liu)范(fan)圍內,導(dao)(dao)通時(shi)二級管的端電(dian)(dian)(dian)(dian)(dian)壓(ya)幾乎維持(chi)不(bu)變,這個電(dian)(dian)(dian)(dian)(dian)壓(ya)稱為(wei)二級管的正(zheng)(zheng)向(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)壓(ya)。