Question
Download Solution PDFWhich of the following statement is true for a wavelength of 1000 nm. A p-n photodiode is fabricated from a semiconductor with band gap of 1.9 eV.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept
A p-n photodiode can only detect those signals whose excitation energy is greater than the band gap energy of the p-n photodiode.
Energy associated with a wave is calculated by the formula
\(E = \frac{hc}{λ}\)
where,
h = plank's constant
c = velocity of the wave i.e. light
λ = wavelength of the signal
Calculation
Given λ = 1000nm = 10-6m
h = 6.6 ×10-34 m2kg/s
c = 3×108 m/s
\(E = \frac{6.6× 10^{-34}× 3× 10^8}{10^{-6}}\)
E = 1.98×10-18J
Now we know that 1eV = 1.6×10-19J
\(E =\frac{1.98× 10^{-19}}{1.6× 10^{-19}}\)
E = 1.23eV
Es < 1.9eV band gap)
Since the energy of the signal is 1.23eV less than the energy band gap (1.9eV) of the semiconductor, Hence the signal cannot be detected by the p-n photodiode.
Last updated on May 26, 2025
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