Modern Physics 6 Question 26
29. The electrical conductivity of a semiconductor increases when electro magnetic radiation of wavelength shorter than $2480 nm$ is incident on it. The band gap (in eV) for the semiconductor is
(1997C, 1M)
(a) 0.9
(b) 0.7
(c) 0.5
(d) 1.1
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Solution:
- $\lambda _{\min }=2480 nm=24800 \AA$
$$ \begin{aligned} \text { Energy }(\text { in eV }) & =\frac{12375}{\lambda}(\text { in } \AA) \\ E & =\frac{12375}{24800} eV, E \approx 0.5 eV \end{aligned} $$
