A student argues that doping silicon with phosphorus atoms must leave the crystal…

PHYSICS · Subjective · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Semiconductor physics and devices · Semiconductor physics and devices

Condensed Matter Physics, Ch Homogeneous semiconductors: counting carriers, doping and mobility

Problem

A student argues that doping silicon with Nd=1.0×1017 cm−3N_d=1.0\times10^{17}\,\mathrm{cm^{-3}} phosphorus atoms must leave the crystal negatively charged, since it now has 101710^{17} extra conduction electrons in every cubic centimetre that were not there before. Evaluate the claim and state what is actually true of the crystal's net charge.

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