$A$ semiconductor $(Ge - As)$ has an energy gap of $1.43\, eV.$ What is the maximum wavelength emitted when a hole and an electron recombine in such semiconductor in $\mathring{A}$?

Which of the following statements concerning the depletion zone of an unbiased $PN$ junction is (are) true?
$(A)$ The width of the zone is independent of the densities of the dopants (impurities).
$(B)$ The width of the zone is dependent on the densities of the dopants.
$(C)$ The electric field in the zone is produced by the ionized dopant atoms.
$(D)$ The electric field in the zone is provided by the electrons in the conduction band and the holes in the valence band.

When a $p-n$ diode is reverse biased,then

In a $P-N$ junction,which of the following statements is correct regarding the potential?

The increase in the width of the depletion region in a $p-n$ junction diode is due to

The cause of the potential barrier in a $p-n$ junction diode is