GATE EC 2014 Question Paper (16-Feb-2014) (Shift 2)

The circuit shown in the figure represents a

The magnitude of current (in mA) through the resistor R₂ in the figure shown is_______.

At T = 300 K, the bandgap and the intrinsic carrier concentration of GaAs are 1.42 eV and 10⁶ cm⁻³, respectively. In order to generate electron-hole pairs in GaAs, which one of the wavelength (${\lambda }_c$) ranges of incident radiation, is most suitable?

(Given that: Plank’s constant is 6.62 × 10⁻³⁴ J-s, the velocity of light is 3 × 10¹⁰ cm/s and charge of an electron is 1.6 × 10⁻¹⁹ C)

In the figure, $\ln ({\mathrm{r}}_{\mathrm{i}})$ is plotted as a function of $1/T$, where ${\mathrm{r}}_{\mathrm{i}}$ is the intrinsic resistivity of silicon, $\mathrm{T}$ is the temperature, and the plot is almost linear



The slope of the line can be used to estimate

The cut-off wavelength $(\mathrm{in}\mu \mathrm{m})$ of light that can be used for intrinsic excitation of a semiconductor material of bandgap $=1.1\mathrm{eV}$ is ________ $\mu \mathrm{m}$.