If we have silicon at 300K with 10 microns of ptype doping o

If we have silicon at 300K with 10 microns of p-type doping of 5*10^17/cc and 10 microns of n-type doping 1000 times less, what is the total resistance in ohms outside the depletion region (use two significant digits). The diode is square with an edge length of 51 microns. Assume p and n mobilities are 500 & 1500 cm^2/(V*s) respectively.

Solution

Resistance R = L /

   Resistivity = 1 /   = 1 / q ( n n + p p )

Where,  n & p are n & p mobilities respectively.

Area A = (51*51) ²= 2601²= 2601*10^-4 cm² = 0.2601cm²

q= 1.6x10¹⁹

=1.6x10¹⁹ (1500*5*10¹⁴+ 500*5*10¹⁷)= 1.6*10^-3*25075= 40.12

= 1 / =1/40.12= 0.0249 ohm-cm

so, R= 0.0249 * 0.001/0.2601 = 9.57