At room temperature, which is more conductive: copper, N-type silicon, or P-type silicon? What are their respective conductivities?
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\$\begingroup\$ What are the doping levels of the silicon? \$\endgroup\$– Elliot AldersonCommented Jun 21, 2020 at 0:36
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\$\begingroup\$ Doping concentration of 10^17 cm^−3 \$\endgroup\$– gstudentCommented Jun 21, 2020 at 1:05
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1\$\begingroup\$ @gstudent Copper, at room temperature, has about \$n=8.49\times 10^{22}\,\frac{\text{electrons}}{\text{cc}}\$. See here for a mobility figure for copper, as well. What do you think? \$\endgroup\$– jonkCommented Jun 21, 2020 at 2:07
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1\$\begingroup\$ Which is more conductive? A semiconductor? Or a conductor? \$\endgroup\$– KazCommented Jun 21, 2020 at 11:10
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2 Answers
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Doped silicon has various conductivities; some wafers [with 60 volt well_substrate sustaining voltage] are about 50 ohm_cm (that is, measured face to face across a 1cm cube, expect 50 ohms). Other materials may be 10 or 100X more conductive.
But copper? A 1cm by 1cm square of PCB copper foil (35 microns thick) is only 0.000500 ohms (that is 500 microOhms) from edge to edge.
If you thicken that foil by 10,000 micron (1cm) / 35 micron, or 280 more layers of PCB foil, your edge-edge measurement will be about 0.000002 ohms (yes --- that is 2 micro Ohms).
Thus the copper is about 1 Million times more conductive than doped silicon.
answered Jun 21, 2020 at 1:58
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As other answers have clarified - copper is far more conductive than doped silicon. Regarding your question on N-type vs P-type; this is related to the concept of Electron and Hole Mobility. Mobility measures how fast electrons (or holes) can move through a material when an electric field is applied.
At a simplistic level, for the same number of charge carriers, conductivity (sigma) of a material is proportional to the mobility (mu):
For doped silicon hole mobility is approximately 1/3 that of electron mobility. As p-type materials have holes as the majority charge carriers; for the same doping concentrations n-type materials will be approximately 3 times more conductive than p-type doped silicon
