Hot-Point Probe Measurements - Engineering Physics

Hot-Point Probe Measurement 

In the case of Four-point probe we have to used the setup of four probes and go through the calculations to know the type of semiconductor. But Hot point probe method is easiest method to investigate that whether the given sample is n-type or p-type semiconductor with the help of simple arrangement of hot probe and cold probe connected to a multi-meter. 

In this arrangement, hot probe is attached to the positive terminal of ammeter and voltmeter and the cold probe is attached to the negative terminal and then placed on the surface of semiconductor. 

In n-type Semiconductor -  When two probes placed on the n-type semiconductor, then the multi-meter shows the positive voltage. The reason behind this is simply the thermal excitation. As we know heat always flow from hotter body to cooler body by the conduction through particles. Here the majority charge carrier flow from hot probe to cold probe. 

In p-type Semiconductor -  When probes touched to the surface of semiconductor, multi-meter shows negative voltage. Here the majority charge carrier is changed, so it give negative voltage.

For Van der Pauw Method - Click Here

For Four-Probe Method - Click Here