深 圳 大 学 实 验 报 告
课程名称: 大学物理实验(一)
实验名称: 实验3 测量二极管的伏安特性
学院: 物理科学与技术学院
专业: 课程编号:
组号: 指导教师:
报告人: 学号:
实验地点 科技楼903
实验时间: 2011 年 05 月 16 日星期 一
实验报告提交时间: 2011 年 05 月 23 日
1、实验目的
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2、实验原理
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3、实验仪器
4、试验内容与步骤
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5、数据记录
正向特性曲线
反向特性曲线
6、数据处理
利用以上两组数据,用坐标分别画出二极管正、负特性曲线
7、实验结果与讨论
(1)为什么反向特性曲线要进行电流修正?
(2)在上述实验中,为何要将电压表内接?若将电流表内接有何不便?已知电流表内阻约为98。
(3)在正向特性曲线中,为何要将电压表的最后一位调为零。
(4)要显示如图7形状的特性曲线,电源的波形采用正弦波比较好,还是锯形波比较好?又如果特性曲线基本上是直线,最好用什么样的波形呢?
(5)如果将测量线路简化图9,并且设,根据自己的实验数据,求出当正向和反向电流均为1.5mA时所对应的电源电压。(提示:)
第二篇:二极管特性曲线
半导体二极管的伏安特性曲线
半导体二极管的核心是PN结,它的特性就是PN结的特性——单向导电性。用实验的方法,在二极管的阳极和阴极两端加上不同极性和不同数值的电压,同时测量流过二极管的电流值,就可得到二极管的伏一安特性曲线。该曲线是非线性的,如图1-13所示。正向特性和反向特性的特点如下。
1.正向特性
当正向电压很低时,正向电流几乎为零,P89LPC954FBD这是因为外加电压的电场还不能克服PN结内部的内电场,内电场阻挡了多数载流子的扩散运动,此时二极管呈现高电阻值,基本上还是处于截止的状态。如图1 - 13所示,正向电压超过二极管开启电压Uon(又称为死区电压)时,电流增长较快,二极管处于导通状态。开启电压与二极管的材料和工作温度有关,通常硅管的开启电压为Uon=0.5V(A点),锗管为Uon=0.1 V(A'点)。二极管导通后,二极管两端的导通压降很低,硅管为0. 6~0.7 V,锗管为0.2~0.3 V如图1-13中B、B'点。
2.反向特性
在分析PN结加上反向电压时,已知少数载流子的漂移运动形成反向电流。因少数载子数量少,且在一定温度下数量基本维持不变,因此,厦向电压在一定范围内增大时,反向电流极微小且基本保持不变,等于反向饱和电流Is。
当反向电压增大到UBR时,外电场能把原子核外层的电子强制拉出来,使半导体内载流子的数目急剧增加,反向电流突然增大,二极管呈现反向击穿的现象如图1-13中D、D'点。二极管被反向击穿后,就失去了单向导电性。二极管反向击穿又分为电击穿和热击穿,利用电击穿可制成稳压管,而热击穿将引起电路故障,使用时一定要注意避免二极管发生反向热击穿的现象。
二极管的特性对温度很敏感。实验表明,当温度升高时,二极管的正向特性曲线将向纵轴移动,开启电压及导通压降都有所减小,反向饱和电流将增大,反向击穿电压也将减小。