List of top Electronics and Communication Engineering Questions on Semiconductors

In an extrinsic semiconductor, the hole concentration is given to be $1.5 n_i$ where $n_i$ is the intrinsic carrier concentration of $1 \times 10^{10} \text{ cm}^{-3}$. The ratio of electron to hole mobility for equal hole and electron drift current is given as ___________ (rounded off to two decimal places).

In a semiconductor device, the Fermi-energy level is 0.35 eV above the valence band energy. The effective density of states in the valence band at T = 300 K is $1 \times 10^{19} \text{ cm}^{-3}$. The thermal equilibrium hole concentration in silicon at 400 K is ___________ $\times 10^{13} \text{ cm}^{-3}$ (rounded off to two decimal places).
Given kT at 300 K is 0.026 eV.

For a MOS capacitor, $V_{fb}$ and $V_t$ are the flat-band voltage and the threshold voltage, respectively. The variation of the depletion width ($W_{\text{dep}}$) for varying gate voltage ($V_g$) is best represented by