Agilent Diode and Transistor Measurement 7-Diode Transistor Measurement c20130117 [1] free download

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Excerpt Edition This PDF is an excerpt from Chapter 7 of the Parametric Measurement Handbook. The Parametric Measurement Handbook Third Edition March 2012 Chapter 7: Diode and Transistor Measurement "Choose a job you love, and you will never have to work a day in your life" -- Confucius Introduction It is not the intent of this handbook to teach a course on semiconductor device physics as there are already an abundance of excellent textbooks available on this subject. However, it is difficult to discuss making parametric diode and transistor measurements without first spending a little time understanding their operation. Therefore, we will give a brief review of pn junctions, diodes, and MOS and bipolar transistor operation with an emphasis on how we characterize them in parametric test as opposed to detailed theoretical derivations. PN junctions and diodes Review of PN diode operation Intrinsic semiconductor materials (such as silicon) do not have an abundance of either electrons or electron holes. However, silicon can be doped with other materials such that it becomes either n-type (possessing excess electrons) or p-type (possessing excess electron holes). When considered individually these materials are not particularly interesting. However, consider the case shown below when these two materials are brought into close contact. p n Q + xp - xn x E Figure 7.1. The cross section of a pn junction assuming an abrupt change from p-doped to n-doped material. The graph shows the fixed charge remaining after the mobile carrier diffusion has stabilized. Assuming the extremely idealized case of an abrupt junction (i.e. one that instantaneously transitions from p to n material) as shown in Figure 7.1, we can see that something very interesting happens. The force of diffusion causes holes from the p-type material to flow into the n-type material (leaving behind fixed