Hall Effect charge carrier trouble

[ronaldoshaky]

Hello.

I recently did a Hall effect experiment with InSb. I did it in two parts. The first with the sample at room temperature and the second immersed in liquid nitrogen. I need some help understanding my results. I used the fomula v_h = (v_1 - v_2) / 2 to work out the Hall voltage (v_h). v_1 and v_2 are measured voltages for different orientations of the sample.

For Part 1 (at room temperature)

I measure voltages v_1 and v_2 for different values of current. I get + voltage for v_1 and - voltage for v_2. this leads to a positive value for v_h when I use the above formula for the Hall voltage. When I plot the Hall voltage against I, I get a positive slope. Can I conclude that the charge carriers are holes?

Part 2 (in Liquid Nitrogen)

Now I get positive values for v_1 and v_2. v_2 is greater than v_1 and this leads to negative values for v_h. when I plot v_h against I, i get a negative slope. Does this mean the charge carriers are now electrons?.

Thank you.

 

[gtoguy97]

Yes, based on the results of your experiment, it appears that the charge carriers in the InSb sample are holes at room temperature and electrons in liquid nitrogen. The positive slope in your first plot indicates that the Hall voltage (v_h) is directly proportional to the current (I). This can be used to infer that the charge carriers are holes. Similarly, in the second plot, the negative slope suggests that the charge carriers are electrons.