Question
Download Solution PDFSilicon is doped with boron to a concentration of 4 × 1017 atoms/cm3. Assume the intrinsic carrier concentration of silicon to be 1.5 × 1010/cm3 and the value of kT/q to be 25 mV at 300 K. Compared to undoped silicon, the Fermi level of doped silicon
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe correct option is 3
Concept:
\({\phi _{fp}} = {E_i} - {E_f}\)
\( = \frac{{KT}}{q}\ln \left( {\frac{{{N_A}}}{{{n_i}}}} \right)\)
\( = 25 \times {10^{ - 3}} \times \ln \left( {\frac{{4 \times {{10}^{17}}}}{{1.5 \times {{10}^{10}}}}} \right)\)
= 0.427 eV
As the impurity is acceptor type the Fermi level goes down by 0.427 eV than the intrinsic level.
Last updated on May 28, 2025
-> UPSC ESE admit card 2025 for the prelims exam has been released.
-> The UPSC IES Prelims 2025 will be held on 8th June 2025.
-> The selection process includes a Prelims and a Mains Examination, followed by a Personality Test/Interview.
-> Candidates should attempt the UPSC IES mock tests to increase their efficiency. The UPSC IES previous year papers can be downloaded here.