$A$ semiconductor is cooled from $T_1 \ K$ to $T_2 \ K$. Its resistance:

If $V_0$ is the volume of a standard unit cell of germanium crystal containing $N_0$ atoms, then the expression for the mass $m$ of a volume $V$ in terms of $V_0, N_0, M$ and $N_A$ is [here, $M$ is the molar mass of germanium and $N_A$ is the Avogadro's constant].

What is the maximum wavelength of electromagnetic radiation that can create an electron-hole pair in a material with a band gap of $0.7 \ eV$? (Planck's constant $h = 4.136 \times 10^{-15} \ eV \cdot s$, velocity of light $c = 3 \times 10^8 \ m/s$).

In a semiconductor,

The probability of electrons to be found in the conduction band of an intrinsic semiconductor at a finite temperature:

Resistivity of a semiconductor depends on