N型MOS管-N型MOS管导通条件及工(gong)作原理、电解方程等详解-KIA MOS管
信息来(lai)源:本(ben)站 日期(qi):2018-08-20
N型(xing)MOS管导(dao)(dao)通(tong)(tong)条件,场效(xiao)(xiao)应管导(dao)(dao)通(tong)(tong)与截止由栅源电(dian)压(ya)来操(cao)控,关于增(zeng)强场效(xiao)(xiao)应管方面来说,N沟道(dao)的(de)管子加(jia)正向(xiang)电(dian)压(ya)即导(dao)(dao)通(tong)(tong),P沟道(dao)的(de)管子则加(jia)反向(xiang)电(dian)压(ya)。一般2V~4V就OK了。可是(shi),场效(xiao)(xiao)应管分(fen)为增(zeng)强型(xing)和(he)耗尽型(xing),增(zeng)强型(xing)的(de)管子是(shi)必须需求加(jia)电(dian)压(ya)才(cai)干导(dao)(dao)通(tong)(tong)的(de),而耗尽型(xing)管子本(ben)来就处于导(dao)(dao)通(tong)(tong)状况,加(jia)栅源电(dian)压(ya)是(shi)为了使(shi)其截止。
开(kai)(kai)关(guan)只(zhi)有两(liang)种状况(kuang)通和断(duan),三极(ji)管(guan)和场(chang)效应管(guan)作(zuo)(zuo)业有三种状况(kuang),1.截(jie)止(zhi),2.线(xian)性(xing)扩大,3.饱满(man)(基极(ji)电(dian)(dian)(dian)(dian)(dian)流(liu)持续添加(jia)而集电(dian)(dian)(dian)(dian)(dian)极(ji)电(dian)(dian)(dian)(dian)(dian)流(liu)不再添加(jia))。使晶(jing)体管(guan)只(zhi)作(zuo)(zuo)业在(zai)1和3状况(kuang)的(de)电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)称之(zhi)为(wei)开(kai)(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu),一般以晶(jing)体管(guan)截(jie)止(zhi),集电(dian)(dian)(dian)(dian)(dian)极(ji)不吸收(shou)电(dian)(dian)(dian)(dian)(dian)流(liu)表(biao)明(ming)开(kai)(kai)关(guan);以晶(jing)体管(guan)饱满(man),发射极(ji)和集电(dian)(dian)(dian)(dian)(dian)极(ji)之(zhi)间的(de)电(dian)(dian)(dian)(dian)(dian)压(ya)差挨(ai)近(jin)(jin)于0V时(shi)表(biao)明(ming)开(kai)(kai)。开(kai)(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)用于数字(zi)电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)时(shi),输出电(dian)(dian)(dian)(dian)(dian)位挨(ai)近(jin)(jin)0V时(shi)表(biao)明(ming)0,输出电(dian)(dian)(dian)(dian)(dian)位挨(ai)近(jin)(jin)电(dian)(dian)(dian)(dian)(dian)源电(dian)(dian)(dian)(dian)(dian)压(ya)时(shi)表(biao)明(ming)1。所以数字(zi)集成电(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)内部的(de)晶(jing)体管(guan)都工(gong)作(zuo)(zuo)在(zai)开(kai)(kai)关(guan)状况(kuang)。场(chang)效应管(guan)按沟道(dao)(dao)分可分为(wei)N沟道(dao)(dao)和P沟道(dao)(dao)管(guan)(在(zai)符号图(tu)中可看到中间的(de)箭头(tou)方(fang)向不一样)。
按资料(liao)可(ke)(ke)分(fen)为(wei)结型(xing)(xing)管(guan)(guan)(guan)和绝(jue)缘(yuan)栅(zha)(zha)型(xing)(xing)管(guan)(guan)(guan),绝(jue)缘(yuan)栅(zha)(zha)型(xing)(xing)又(you)分(fen)为(wei)耗尽型(xing)(xing)和增(zeng)(zeng)强型(xing)(xing),一般主板上(shang)大(da)(da)(da)多是(shi)绝(jue)缘(yuan)栅(zha)(zha)型(xing)(xing)管(guan)(guan)(guan)简称(cheng)MOS管(guan)(guan)(guan),而(er)且大(da)(da)(da)多选用增(zeng)(zeng)强型(xing)(xing)的(de)N沟道(dao)(dao),其次(ci)是(shi)增(zeng)(zeng)强型(xing)(xing)的(de)P沟道(dao)(dao),结型(xing)(xing)管(guan)(guan)(guan)和耗尽型(xing)(xing)管(guan)(guan)(guan)简直不用。 场(chang)效应(ying)晶(jing)体(ti)(ti)(ti)管(guan)(guan)(guan)简称(cheng)场(chang)效应(ying)管(guan)(guan)(guan).由大(da)(da)(da)都载流(liu)(liu)子参加导电,也称(cheng)为(wei)单极(ji)(ji)型(xing)(xing)晶(jing)体(ti)(ti)(ti)管(guan)(guan)(guan).它归于电压操(cao)控型(xing)(xing)半导体(ti)(ti)(ti)器(qi)材(cai). 场(chang)效应(ying)管(guan)(guan)(guan)是(shi)使(shi)(shi)用大(da)(da)(da)都载流(liu)(liu)子导电,所(suo)以称(cheng)之为(wei)单极(ji)(ji)型(xing)(xing)器(qi)材(cai),而(er)晶(jing)体(ti)(ti)(ti)管(guan)(guan)(guan)是(shi)即有大(da)(da)(da)都载流(liu)(liu)子,也使(shi)(shi)用少量载流(liu)(liu)子导电,被(bei)称(cheng)之为(wei)双极(ji)(ji)型(xing)(xing)器(qi)材(cai). 有些(xie)场(chang)效应(ying)管(guan)(guan)(guan)的(de)源极(ji)(ji)和漏极(ji)(ji)能够交换使(shi)(shi)用,栅(zha)(zha)压也可(ke)(ke)正可(ke)(ke)负,灵活性比晶(jing)体(ti)(ti)(ti)管(guan)(guan)(guan)好。备(bei)注:标注的(de)ID电流(liu)(liu)是(shi)MOS管(guan)(guan)(guan)
在(zai)一(yi)块掺杂浓度较低(di)的P型硅(gui)衬底上(shang)(shang),制造(zao)两个高掺杂浓度的N+区,并用金属(shu)铝(lv)引(yin)出(chu)两个电极(ji),分别作漏极(ji)d和源极(ji)s。然后在(zai)半导体外表掩盖一(yi)层(ceng)(ceng)很薄的二氧化硅(gui)(SiO2)绝缘(yuan)层(ceng)(ceng),在(zai)漏——源极(ji)间的绝缘(yuan)层(ceng)(ceng)上(shang)(shang)再装上(shang)(shang)一(yi)个铝(lv)电极(ji),作为栅极(ji)g。
在衬底上也引出一个电极B,这就构成了一个N沟道加强型MOS管。MOS管的源极和衬底通常是接在一同的(大多数管子在出厂前已连接好)。它的栅极与其它电极间是绝缘的。图(a)、(b)分别是它的构造表示图和代表符号。代表符号中的箭头方向表示由P(衬底)指向N(沟道)。P沟道加强型MOS管的箭头方向与上述相反,如图(c)所示。
(1)vGS对(dui)iD及沟道的控制造(zao)用
① vGS=0 的状况
从图1(a)能(neng)够看出(chu),加强型MOS管的(de)漏极(ji)d和源(yuan)极(ji)s之间(jian)有(you)两个背靠背的(de)PN结。当栅——源(yuan)电(dian)压(ya)(ya)vGS=0时,即便(bian)加上漏——源(yuan)电(dian)压(ya)(ya)vDS,而且(qie)不(bu)管vDS的(de)极(ji)性(xing)如何,总有(you)一个PN结处(chu)于(yu)反(fan)偏状态(tai),漏——源(yuan)极(ji)间(jian)没有(you)导电(dian)沟(gou)道,所(suo)以这时漏极(ji)电(dian)流iD≈0。
② vGS>0 的状况
若vGS>0,则栅极和(he)衬底之(zhi)间的SiO2绝缘(yuan)层(ceng)中便产(chan)生一个(ge)电(dian)场(chang)(chang)。电(dian)场(chang)(chang)方向垂直于半导体(ti)外表(biao)的由栅极指向衬底的电(dian)场(chang)(chang)。这个(ge)电(dian)场(chang)(chang)能排挤空穴而(er)吸收电(dian)子。
排挤空(kong)穴:使栅极左(zuo)近(jin)的(de)(de)P型(xing)(xing)衬(chen)底(di)(di)中的(de)(de)空(kong)穴被(bei)排挤,剩(sheng)下不能挪动的(de)(de)受主离子(负离子),构(gou)成耗尽层。吸收(shou)电子:将 P型(xing)(xing)衬(chen)底(di)(di)中的(de)(de)电子(少子)被(bei)吸收(shou)到衬(chen)底(di)(di)外表。
(2)导电沟(gou)道的构成:
当vGS数值较小,吸收(shou)电(dian)(dian)(dian)子(zi)(zi)的(de)才能不强(qiang)时,漏(lou)——源(yuan)极(ji)(ji)之(zhi)间仍(reng)无导(dao)(dao)电(dian)(dian)(dian)沟(gou)道(dao)呈现,如(ru)图1(b)所示。vGS增加(jia)时,吸收(shou)到(dao)P衬(chen)(chen)底外(wai)表(biao)层的(de)电(dian)(dian)(dian)子(zi)(zi)就(jiu)增加(jia),当vGS到(dao)达某一(yi)数值时,这些电(dian)(dian)(dian)子(zi)(zi)在栅极(ji)(ji)左近的(de)P衬(chen)(chen)底外(wai)表(biao)便构成(cheng)一(yi)个N型(xing)(xing)薄(bo)层,且(qie)与(yu)两个N+区相连(lian)通,在漏(lou)——源(yuan)极(ji)(ji)间构成(cheng)N型(xing)(xing)导(dao)(dao)电(dian)(dian)(dian)沟(gou)道(dao),其导(dao)(dao)电(dian)(dian)(dian)类型(xing)(xing)与(yu)P衬(chen)(chen)底相反,故又(you)称为反型(xing)(xing)层,如(ru)图1(c)所示。vGS越(yue)大(da),作用于半导(dao)(dao)体(ti)外(wai)表(biao)的(de)电(dian)(dian)(dian)场就(jiu)越(yue)强(qiang),吸收(shou)到(dao)P衬(chen)(chen)底外(wai)表(biao)的(de)电(dian)(dian)(dian)子(zi)(zi)就(jiu)越(yue)多,导(dao)(dao)电(dian)(dian)(dian)沟(gou)道(dao)越(yue)厚,沟(gou)道(dao)电(dian)(dian)(dian)阻越(yue)小。
开端构成沟(gou)道(dao)时的栅——源极电(dian)(dian)压(ya)称(cheng)为开启电(dian)(dian)压(ya),用VT表示。
上(shang)面讨论的N沟道MOS管(guan)在(zai)vGS<VT时,不能(neng)构成(cheng)(cheng)导电沟道,管(guan)子处于截止状态。只要当vGS≥VT时,才有沟道构成(cheng)(cheng)。这种必需在(zai)vGS≥VT时才干构成(cheng)(cheng)导电沟道的MOS管(guan)称为加强(qiang)型(xing)MOS管(guan)。沟道构成(cheng)(cheng)以后,在(zai)漏——源极(ji)间(jian)加上(shang)正向电压vDS,就有漏极(ji)电流产生(sheng)。
(1)特性(xing)曲线和电流方程
1)输出特性曲(qu)线(xian)
N沟道加强型(xing)MOS管的输(shu)出特性(xing)曲(qu)线如图1(a)所示。与(yu)结型(xing)场效(xiao)应管一样,其输(shu)出特性(xing)曲(qu)线也可(ke)分为可(ke)变电阻(zu)区(qu)(qu)、饱(bao)和(he)区(qu)(qu)、截止区(qu)(qu)和(he)击穿区(qu)(qu)几局部。
2)转移特性曲线
转(zhuan)移(yi)特(te)性曲(qu)(qu)线(xian)如图1(b)所(suo)示,由于场效应管(guan)作(zuo)放大器件运用(yong)时(shi)是工作(zuo)在饱(bao)和(he)区(qu)(恒流区(qu)),此时(shi)iD简直不(bu)随vDS而变化,即不(bu)同的vDS所(suo)对应的转(zhuan)移(yi)特(te)性曲(qu)(qu)线(xian)简直是重合的,所(suo)以可用(yong)vDS大于某一(yi)数值(vDS>vGS-VT)后的一(yi)条转(zhuan)移(yi)特(te)性曲(qu)(qu)线(xian)替代饱(bao)和(he)区(qu)的一(yi)切转(zhuan)移(yi)特(te)性曲(qu)(qu)线(xian)。
3)iD与vGS的近(jin)似关系
与(yu)结型场(chang)效(xiao)应(ying)管相相似。在饱和区内,iD与(yu)vGS的近(jin)似关(guan)系式为
(2)参数(shu)
MOS管(guan)的(de)主要参数与结型(xing)场(chang)效应管(guan)根本(ben)相同,只是加强(qiang)型(xing)MOS管(guan)中(zhong)不用夹(jia)断电(dian)压(ya)VP ,而用开(kai)启电(dian)压(ya)VT表(biao)征管(guan)子(zi)的(de)特(te)性(xing)。
N沟道(dao)耗尽型MOS管的(de)基本结构
(1)构(gou)造(zao):
N沟道耗尽型MOS管与N沟道加强型MOS管根(gen)本类似。
(2)区别(bie):
耗尽(jin)型MOS管在vGS=0时(shi),漏——源(yuan)极间已有(you)导(dao)电沟道(dao)产生,而(er)加强(qiang)型MOS管要(yao)在vGS≥VT时(shi)才呈现导(dao)电沟道(dao)。
(3)缘(yuan)由(you):
沟(gou)道耗尽型MOS管时掺入负离子),如(ru)图1(a)所示,因而即便(bian)vGS=0时,在这些正离子产生的(de)电场(chang)作用下,漏——源极间的(de)P型衬底外(wai)表也能感应(ying)生成N沟(gou)道(称为初始沟(gou)道),只需(xu)加(jia)上正向电压(ya)vDS,就有电流iD。
假(jia)如加上正的(de)(de)vGS,栅极与N沟(gou)道(dao)(dao)(dao)间(jian)的(de)(de)电(dian)场(chang)将在沟(gou)道(dao)(dao)(dao)中(zhong)吸收来更多的(de)(de)电(dian)子(zi),沟(gou)道(dao)(dao)(dao)加宽,沟(gou)道(dao)(dao)(dao)电(dian)阻(zu)变(bian)小,iD增大。反之vGS为(wei)负时,沟(gou)道(dao)(dao)(dao)中(zhong)感应的(de)(de)电(dian)子(zi)减少,沟(gou)道(dao)(dao)(dao)变(bian)窄(zhai),沟(gou)道(dao)(dao)(dao)电(dian)阻(zu)变(bian)大,iD减小。当(dang)vGS负向增加到某一(yi)数值时,导(dao)电(dian)沟(gou)道(dao)(dao)(dao)消逝,iD趋于零,管(guan)子(zi)截止(zhi),故称为(wei)耗尽(jin)型。
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