$A$ crystal diode is a:

The diode shown in the circuit is a silicon diode. The potential difference between the points $A$ and $B$ will be.....$V$

When a $p-n$ junction diode is forward biased,

The energy of a photon in a monochromatic light of wavelength $621 \ nm$ matches with the band gap of a semiconducting material. Then the minimum energy required to create an electron-hole pair from the semiconductor is
[Take $hc = 1242 \ eV-nm$,where $h$ is Planck's constant and $c$ is speed of light in vacuum] (in $eV$)

The depletion layer consists of

When a forward bias is applied to a $p-n$ junction,it $\qquad$ .