Name the primary constitutional unit of semiconductor composition.

Three semiconductors are arranged in the increasing order of their energy gap as follows. The correct arrangement is:

Although carbon,silicon,and germanium have the same lattice structure and four valence electrons each,their band structure leads to the energy gaps as:

When radiation with a wavelength shorter than $2480 \, nm$ is incident on a semiconductor,its conductivity increases. The bandgap of this semiconductor is ....... $eV$.

$A$ solid which is not transparent to visible light and whose conductivity increases with temperature is formed by

Pure sodium $(Na)$ is a good conductor of electricity because the $3s$ and $3p$ atomic bands overlap to form a partially filled conduction band. By contrast,the ionic sodium chloride $(NaCl)$ crystal is: