Holes are being steadily injected into a region of n-type silicon (connected to

Question

Holes are being steadily injected into a region of n-type silicon (connected to other devices, the details of which are not important for this question). In the steady state, the excess-hole concentration profile shown in Fig. P3.10 is established in the n-type silicon region. Here “excess” means over and above the thermal-equilibrium concentration (in the absence of hole injection), denoted pn0. If ND = 1016/cm3 , ni = 1.5×1010/cm3 , Dp = 12 cm2 /s, and W = 50 nm, find the density of the current that will flow in the x direction.

Figure P3.10

Explanation / Answer

n=ND=1016/cm3

Pno=ni2/n=1020/1016=104/cm3

dP/dx=108(Pno-Pno)/W=(108*104/cm3)   

____________ =1017/cm4

0.1*10-4 cm

Jp=q*Dp*dp/dx=1.6*10-19*12*1017

=0.192 A/cm2

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