Question
Download Solution PDFThe concentration of hole-electron pairs in pure silicon at T = 350 K is 7 × 1015 per cubic meter. Antinomy is doped into silicon in a proportion of 1 atom in 107 atoms. Assuming that half of the impurity atoms contribute electrons in the conduction band, the factor by which the number of charge carriers increases due to doping (the number of silicon atoms per cubic meter is 5 × 1028) is
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThe intrinsic carrier concentration = 7 × 1015 cm-3
The semiconductor is doped with antimony (group 5 element) in the proportion of 1 atom in 107 atoms.
Number of donor atoms = \(\frac{1}{10^7}\) × number of silicon atoms
= 5 × 1021 atoms/ cm3
∵ half of the impurity atoms get ionized and sends electrons in the conduction band.
The factor by which charge carriers increases is:
\(\frac{2.5 × 10^{21}}{7× 10^{15}}\)= 0.35 × 106 = 3.5 × 105
The closest option is d.
Last updated on Jul 2, 2025
-> ESE Mains 2025 exam date has been released. As per the schedule, UPSC IES Mains exam 2025 will be conducted on August 10.
-> UPSC ESE result 2025 has been released. Candidates can download the ESE prelims result PDF from here.
-> 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.