场效应(ying)管(guan)工作原理动画在线视频-场效应(ying)管(guan)结构与符号等详(xiang)解-KIA MOS管(guan)
信(xin)息(xi)来(lai)源：本站 日(ri)期：2018-11-09
场效(xiao)应晶(jing)体(ti)(ti)管(guan)(guan)（Field Effect Transistor缩(suo)写(FET)）简称场效(xiao)应管(guan)(guan)。主要有两(liang)种类型（junction FET—JFET)和(he)金属(shu) - 氧(yang)化物半导体(ti)(ti)场效(xiao)应管(guan)(guan)（metal-oxide semiconductor FET，简称MOS-FET）。由(you)多数载流子参与导电(dian)(dian)(dian)，也(ye)称为单极(ji)型晶(jing)体(ti)(ti)管(guan)(guan)。它属(shu)于电(dian)(dian)(dian)压控制型半导体(ti)(ti)器(qi)件。具有输入电(dian)(dian)(dian)阻高（107～1015Ω）、噪声(sheng)小、功耗(hao)低(di)、动态范围大、易(yi)于集成、没有二次(ci)击穿(chuan)现象、安(an)全工(gong)作区(qu)域宽(kuan)等(deng)优(you)点，现已(yi)成为双极(ji)型晶(jing)体(ti)(ti)管(guan)(guan)和(he)功率晶(jing)体(ti)(ti)管(guan)(guan)的强大竞(jing)争者。
场效应管（FET）是利用控(kong)制(zhi)输入回路的(de)(de)电场效应来控(kong)制(zhi)输出回路电流的(de)(de)一种半(ban)(ban)导体(ti)(ti)器件，并以此命(ming)名(ming)。由于它(ta)仅靠半(ban)(ban)导体(ti)(ti)中的(de)(de)多数载流子导电，又称单(dan)极(ji)型晶(jing)体(ti)(ti)管。
场效应管工作原(yuan)理用(yong)一句(ju)话(hua)说，就是“漏(lou)极(ji)-源(yuan)极(ji)间(jian)流经(jing)沟(gou)道(dao)的(de)(de)(de)(de)(de)(de)ID，用(yong)以(yi)栅极(ji)与沟(gou)道(dao)间(jian)的(de)(de)(de)(de)(de)(de)pn结形成(cheng)的(de)(de)(de)(de)(de)(de)反偏(pian)的(de)(de)(de)(de)(de)(de)栅极(ji)电压控制ID”。更正(zheng)确(que)地说，ID流经(jing)通路(lu)的(de)(de)(de)(de)(de)(de)宽度，即沟(gou)道(dao)截面积，它是由pn结反偏(pian)的(de)(de)(de)(de)(de)(de)变化，产生耗尽层扩(kuo)展变化控制的(de)(de)(de)(de)(de)(de)缘故。在(zai)VGS=0的(de)(de)(de)(de)(de)(de)非饱(bao)和(he)区(qu)域，表示的(de)(de)(de)(de)(de)(de)过渡层的(de)(de)(de)(de)(de)(de)扩(kuo)展因(yin)为不(bu)很大，根据漏(lou)极(ji)-源(yuan)极(ji)间(jian)所加VDS的(de)(de)(de)(de)(de)(de)电场，源(yuan)极(ji)区(qu)域的(de)(de)(de)(de)(de)(de)某(mou)些电子(zi)被(bei)漏(lou)极(ji)拉去，即从漏(lou)极(ji)向源(yuan)极(ji)有(you)电流ID流动。从门极(ji)向漏(lou)极(ji)扩(kuo)展的(de)(de)(de)(de)(de)(de)过度层将(jiang)沟(gou)道(dao)的(de)(de)(de)(de)(de)(de)一部分构成(cheng)堵(du)塞型，ID饱(bao)和(he)。将(jiang)这种状(zhuang)态称(cheng)为夹断。这意味着过渡层将(jiang)沟(gou)道(dao)的(de)(de)(de)(de)(de)(de)一部分阻挡，并不(bu)是电流被(bei)切断。
在过(guo)(guo)渡(du)层(ceng)由(you)于没有(you)电(dian)(dian)子、空穴的自由(you)移(yi)(yi)动，在理想(xiang)状态(tai)下几(ji)(ji)乎具有(you)绝缘特性，通常(chang)电(dian)(dian)流也难流动。但是(shi)此(ci)时漏极(ji)-源极(ji)间的电(dian)(dian)场(chang)，实际上是(shi)两个过(guo)(guo)渡(du)层(ceng)接触漏极(ji)与门(men)极(ji)下部(bu)附近，由(you)于漂(piao)移(yi)(yi)电(dian)(dian)场(chang)拉(la)去的高速电(dian)(dian)子通过(guo)(guo)过(guo)(guo)渡(du)层(ceng)。因漂(piao)移(yi)(yi)电(dian)(dian)场(chang)的强(qiang)度几(ji)(ji)乎不(bu)变产生ID的饱和现象。其次，VGS向(xiang)(xiang)负的方(fang)向(xiang)(xiang)变化，让VGS=VGS(off)，此(ci)时过(guo)(guo)渡(du)层(ceng)大(da)(da)致成为覆盖全区域的状态(tai)。而且VDS的电(dian)(dian)场(chang)大(da)(da)部(bu)分加到过(guo)(guo)渡(du)层(ceng)上，将电(dian)(dian)子拉(la)向(xiang)(xiang)漂(piao)移(yi)(yi)方(fang)向(xiang)(xiang)的电(dian)(dian)场(chang)，只(zhi)有(you)靠近源极(ji)的很短(duan)部(bu)分，这更使电(dian)(dian)流不(bu)能流通。
MOS场效(xiao)(xiao)应(ying)管(guan)也(ye)被(bei)称为(wei)(wei)金属氧化物(wu)半导(dao)体(ti)场效(xiao)(xiao)应(ying)管(guan)(MetalOxideSemiconductor FieldEffect Transistor, MOSFET)。它一般有(you)耗尽型(xing)(xing)和(he)增(zeng)(zeng)强型(xing)(xing)两(liang)种。增(zeng)(zeng)强型(xing)(xing)MOS场效(xiao)(xiao)应(ying)管(guan)可(ke)分为(wei)(wei)NPN型(xing)(xing)PNP型(xing)(xing)。NPN型(xing)(xing)通常称为(wei)(wei)N沟(gou)道(dao)型(xing)(xing)，PNP型(xing)(xing)也(ye)叫(jiao)P沟(gou)道(dao)型(xing)(xing)。对于N沟(gou)道(dao)的(de)(de)场效(xiao)(xiao)应(ying)管(guan)其源极(ji)和(he)漏极(ji)接在(zai)N型(xing)(xing)半导(dao)体(ti)上，同样(yang)对于P沟(gou)道(dao)的(de)(de)场效(xiao)(xiao)应(ying)管(guan)其源极(ji)和(he)漏极(ji)则(ze)接在(zai)P型(xing)(xing)半导(dao)体(ti)上。场效(xiao)(xiao)应(ying)管(guan)的(de)(de)输(shu)出电(dian)(dian)流是由输(shu)入的(de)(de)电(dian)(dian)压（或(huo)称电(dian)(dian)场）控制，可(ke)以认为(wei)(wei)输(shu)入电(dian)(dian)流极(ji)小或(huo)没有(you)输(shu)入电(dian)(dian)流，这使得该器件有(you)很高的(de)(de)输(shu)入阻抗，同时这也(ye)是我们称之为(wei)(wei)场效(xiao)(xiao)应(ying)管(guan)的(de)(de)原因。
在(zai)二(er)(er)极(ji)(ji)(ji)管加(jia)(jia)上正(zheng)(zheng)(zheng)向电(dian)(dian)(dian)压（P端(duan)(duan)(duan)接正(zheng)(zheng)(zheng)极(ji)(ji)(ji)，N端(duan)(duan)(duan)接负(fu)(fu)(fu)(fu)极(ji)(ji)(ji)）时，二(er)(er)极(ji)(ji)(ji)管导(dao)通(tong)，其PN结有(you)电(dian)(dian)(dian)流(liu)(liu)通(tong)过。这(zhei)是因为在(zai)P型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)为正(zheng)(zheng)(zheng)电(dian)(dian)(dian)压时，N型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)内的(de)(de)(de)负(fu)(fu)(fu)(fu)电(dian)(dian)(dian)子被(bei)吸引(yin)而(er)(er)(er)涌向加(jia)(jia)有(you)正(zheng)(zheng)(zheng)电(dian)(dian)(dian)压的(de)(de)(de)P型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)，而(er)(er)(er)P型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)内的(de)(de)(de)正(zheng)(zheng)(zheng)电(dian)(dian)(dian)子则朝N型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)运动，从而(er)(er)(er)形成导(dao)通(tong)电(dian)(dian)(dian)流(liu)(liu)。同理，当(dang)二(er)(er)极(ji)(ji)(ji)管加(jia)(jia)上反(fan)向电(dian)(dian)(dian)压（P端(duan)(duan)(duan)接负(fu)(fu)(fu)(fu)极(ji)(ji)(ji)，N端(duan)(duan)(duan)接正(zheng)(zheng)(zheng)极(ji)(ji)(ji)）时，这(zhei)时在(zai)P型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)为负(fu)(fu)(fu)(fu)电(dian)(dian)(dian)压，正(zheng)(zheng)(zheng)电(dian)(dian)(dian)子被(bei)聚(ju)集在(zai)P型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)，负(fu)(fu)(fu)(fu)电(dian)(dian)(dian)子则聚(ju)集在(zai)N型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)端(duan)(duan)(duan)，电(dian)(dian)(dian)子不移动，其PN结没(mei)有(you)电(dian)(dian)(dian)流(liu)(liu)通(tong)过，二(er)(er)极(ji)(ji)(ji)管截止。在(zai)栅极(ji)(ji)(ji)没(mei)有(you)电(dian)(dian)(dian)压时，由前面分析(xi)可知，在(zai)源极(ji)(ji)(ji)与(yu)漏(lou)极(ji)(ji)(ji)之(zhi)间(jian)(jian)不会有(you)电(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)过，此时场效(xiao)应管处与(yu)截止状态。当(dang)有(you)一(yi)个正(zheng)(zheng)(zheng)电(dian)(dian)(dian)压加(jia)(jia)在(zai)N沟道(dao)的(de)(de)(de)MOS场效(xiao)应管栅极(ji)(ji)(ji)上时，由于(yu)电(dian)(dian)(dian)场的(de)(de)(de)作用，此时N型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)的(de)(de)(de)源极(ji)(ji)(ji)和(he)漏(lou)极(ji)(ji)(ji)的(de)(de)(de)负(fu)(fu)(fu)(fu)电(dian)(dian)(dian)子被(bei)吸引(yin)出来而(er)(er)(er)涌向栅极(ji)(ji)(ji)，但由于(yu)氧化膜的(de)(de)(de)阻(zu)挡，使得电(dian)(dian)(dian)子聚(ju)集在(zai)两个N沟道(dao)之(zhi)间(jian)(jian)的(de)(de)(de)P型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)，从而(er)(er)(er)形成电(dian)(dian)(dian)流(liu)(liu)，使源极(ji)(ji)(ji)和(he)漏(lou)极(ji)(ji)(ji)之(zhi)间(jian)(jian)导(dao)通(tong)。可以想像(xiang)为两个N型(xing)(xing)半(ban)(ban)(ban)(ban)导(dao)体(ti)(ti)(ti)之(zhi)间(jian)(jian)为一(yi)条沟，栅极(ji)(ji)(ji)电(dian)(dian)(dian)压的(de)(de)(de)建立相当(dang)于(yu)为它们之(zhi)间(jian)(jian)搭了一(yi)座桥梁，该桥的(de)(de)(de)大小(xiao)由栅压的(de)(de)(de)大小(xiao)决定。
电(dian)(dian)(dian)路将一(yi)个增强型P沟道MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)和一(yi)个增强型N沟道MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)组合在(zai)(zai)一(yi)起使(shi)用(yong)。当(dang)输入端为(wei)(wei)低电(dian)(dian)(dian)平时，P沟道MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)导通(tong)(tong)，输出(chu)端与(yu)电(dian)(dian)(dian)源正(zheng)极接(jie)通(tong)(tong)。当(dang)输入端为(wei)(wei)高电(dian)(dian)(dian)平时，N沟道MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)导通(tong)(tong)，输出(chu)端与(yu)电(dian)(dian)(dian)源地(di)接(jie)通(tong)(tong)。在(zai)(zai)该(gai)电(dian)(dian)(dian)路中，P沟道MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)和N沟道MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)总是在(zai)(zai)相(xiang)反的状态下工(gong)作(zuo)，其相(xiang)位输入端和输出(chu)端相(xiang)反。通(tong)(tong)过这种工(gong)作(zuo)方式(shi)我们(men)可以获得(de)较(jiao)大的电(dian)(dian)(dian)流(liu)(liu)输出(chu)。同(tong)(tong)时由于(yu)漏电(dian)(dian)(dian)流(liu)(liu)的影响，使(shi)得(de)栅压(ya)(ya)在(zai)(zai)还(hai)没(mei)有到(dao)0V，通(tong)(tong)常在(zai)(zai)栅极电(dian)(dian)(dian)压(ya)(ya)小于(yu)1到(dao)2V时，MOS场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)既被关(guan)断。不同(tong)(tong)场效(xiao)(xiao)(xiao)应(ying)(ying)管(guan)(guan)(guan)(guan)(guan)其关(guan)断电(dian)(dian)(dian)压(ya)(ya)略有不同(tong)(tong)。也正(zheng)因(yin)为(wei)(wei)如此，使(shi)得(de)该(gai)电(dian)(dian)(dian)路不会(hui)因(yin)为(wei)(wei)两(liang)管(guan)(guan)(guan)(guan)(guan)同(tong)(tong)时导通(tong)(tong)而(er)造成电(dian)(dian)(dian)源短路。
MOS管(guan)，在(zai)一块掺杂(za)浓度较低的P型半(ban)导体硅衬底上(shang)，用(yong)半(ban)导体光刻、扩(kuo)散工艺(yi)制作两(liang)个(ge)(ge)高掺杂(za)浓度的N+区(qu)，并(bing)用(yong)金属铝引出两(liang)个(ge)(ge)电(dian)极(ji)(ji)(ji)，分别作为漏极(ji)(ji)(ji)D和(he)(he)源极(ji)(ji)(ji)S。然(ran)后(hou)在(zai)漏极(ji)(ji)(ji)和(he)(he)源极(ji)(ji)(ji)之(zhi)间的P型半(ban)导体表面复盖一层很薄的二氧化(hua)硅（Si02）绝(jue)缘层膜，在(zai)再(zai)这(zhei)个(ge)(ge)绝(jue)缘层膜上(shang)装上(shang)一个(ge)(ge)铝电(dian)极(ji)(ji)(ji)，作为栅(zha)极(ji)(ji)(ji)G。这(zhei)就构(gou)成了一个(ge)(ge)N沟道(dao)（NPN型）增(zeng)强型MOS管(guan)。显然(ran)它的栅(zha)极(ji)(ji)(ji)和(he)(he)其它电(dian)极(ji)(ji)(ji)间是(shi)绝(jue)缘的。下图(tu)所示(shi)分别是(shi)它的结构(gou)图(tu)和(he)(he)代表符号(hao)。
同样用(yong)上述相同的(de)方法(fa)在一块掺(chan)杂(za)浓(nong)度(du)较低的(de)N型(xing)半导体硅衬底上，用(yong)半导体光刻、扩散(san)工艺制作(zuo)(zuo)两个高掺(chan)杂(za)浓(nong)度(du)的(de)P+区，及上述相同的(de)栅极(ji)制作(zuo)(zuo)过程，就(jiu)制成为一个P沟道（PNP型(xing)）增强型(xing)MOS管。如上图(tu)所示分别是P沟道MOS管道结(jie)构图(tu)和代表符号。
N沟(gou)道(dao)MOS管(guan)的符号，图中D是(shi)(shi)(shi)(shi)漏极(ji)，S是(shi)(shi)(shi)(shi)源极(ji)，G是(shi)(shi)(shi)(shi)栅极(ji)，中间的箭(jian)头(tou)(tou)表(biao)示(shi)(shi)衬(chen)底，如果箭(jian)头(tou)(tou)向里表(biao)示(shi)(shi)是(shi)(shi)(shi)(shi)N沟(gou)道(dao)的MOS管(guan)，箭(jian)头(tou)(tou)向外表(biao)示(shi)(shi)是(shi)(shi)(shi)(shi)P沟(gou)道(dao)的MOS管(guan)。
在(zai)实际MOS管(guan)生产的过(guo)程中(zhong)衬底在(zai)出厂(chang)前就(jiu)和源极连接(jie)，所(suo)以在(zai)符号的规则中(zhong)；表(biao)示衬底的箭(jian)头也必须和源极相连接(jie)，以区别漏极和源极。上(shang)图是P沟道MOS管(guan)的符号。
大功率MOS管(guan)(guan)(guan)应用(yong)电压(ya)(ya)的(de)极(ji)(ji)(ji)(ji)性和我们普通的(de)晶(jing)(jing)体(ti)三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)(guan)相同(tong)，N沟道的(de)类似NPN晶(jing)(jing)体(ti)三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)(guan)，漏(lou)极(ji)(ji)(ji)(ji)D接(jie)正极(ji)(ji)(ji)(ji)，源(yuan)极(ji)(ji)(ji)(ji)S接(jie)负(fu)极(ji)(ji)(ji)(ji)，栅极(ji)(ji)(ji)(ji)G正电压(ya)(ya)时导电沟道建立，N沟道MOS管(guan)(guan)(guan)开(kai)始工作(zuo)(zuo),如下图所示。同(tong)样P道的(de)类似PNP晶(jing)(jing)体(ti)三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)(guan)，漏(lou)极(ji)(ji)(ji)(ji)D接(jie)负(fu)极(ji)(ji)(ji)(ji)，源(yuan)极(ji)(ji)(ji)(ji)S接(jie)正极(ji)(ji)(ji)(ji)，栅极(ji)(ji)(ji)(ji)G负(fu)电压(ya)(ya)时，导电沟道建立，P沟道MOS管(guan)(guan)(guan)开(kai)始工作(zuo)(zuo),如下图所示。
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