Hot-point probe

{{short description|Electrical probe for analysis of semiconductor components}}

A hot point probe is a method of quickly determining whether a semiconductor sample is n-type or p-type. The sample is probed using a voltmeter or ammeter and a heat source, such as a soldering iron, is placed on one of the leads. The heat will cause charge carriers (electrons in n-type, holes in p-type) to move away from the lead. The heat from the probe creates an increased number of carriers, which then diffuse away from the contact point. This causes a current/voltage difference.

For example, if the heat source is placed on the positive lead of a voltmeter attached to an n-type semiconductor, a positive voltage reading will result as the area around the heat source/positive lead becomes positively charged.{{Cite web |url=http://fabweb.ece.uiuc.edu:1999/Equipment/HotPointProbes/Instructions.html |title=The Hot Point Probes |website=ECE Illinois|access-date=2009-10-06 |archive-url=https://web.archive.org/web/20100616201938/http://fabweb.ece.uiuc.edu:1999/Equipment/HotPointProbes/Instructions.html |archive-date=2010-06-16 |url-status=dead }} A simple explanation is that the thermally-excited majority free carriers move from the hot probe to the cold probe. The mechanism for this motion with in semiconductor is diffusion type since the material is uniformly doped.{{cite web |title=2.4.7.9 The "hot-probe" experiment |url=https://ecee.colorado.edu/~bart/book/hotprobe.htm |website=ecee.colorado.edu |access-date=27 November 2020 |archive-date=6 March 2021 |archive-url=https://web.archive.org/web/20210306224540/https://ecee.colorado.edu/~bart/book/hotprobe.htm |url-status=dead }}