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Q.
An n-type semiconductor is formed
Semiconductor Electronics: Materials Devices and Simple Circuits
Solution:
Pentavalent impurity atom i.e., atoms having 5 valence electrons such as antimony (Sb) or arsenic (As), when added to a pure semiconductor, produce excess of free electrons i.e., donor electrons to the semiconductor. For this reason, pentavalent impurity atoms are called donor impurity atom. The semiconductor so produced is called n-type extrinsic semiconductor
So the corresponding wavelength is equal to,
$ \, \, \, \, \lambda=\frac{hc}{E} =\frac{6.67 \times 10^{-34} \times 3 \times 10^{8}}{1.5 \times 1.6 \times 10^{-19}}$
$ \, \, \, \, \, \, \, =8.3375 \times 10^{-26} \times 10^{19} =8337.5 \mathring{A}$