GATE EC 2012 Set 1 Q1 — Electronic Devices

Consider carrier transport in a Zener diode in the breakdown region. Which is the dominant transport mechanism for current flow in this case?

Consider the circuit shown in the Figure with $V_{i}=3 \mathrm{~V}$ and $V_{C C}=12 \mathrm{~V}$. Assume $V_{B E}=0.7 \mathrm{~V}$ and $\beta_{d c}=99$ for the BJT. Which of the following options is the correct value of the current $\boldsymbol{I}_{\boldsymbol{o}}$ ?

Consider a $\text{p-n}$ junction diode when it is forward biased with $2$ V. Which of the following is/are the correct magnitude(s) of the energy difference between quasi Fermi-levels, $E_{f n}$ in the $\text{n -side}$ and $E_{f p}$ in the $\text{p -side}?$

Figure shows the output characteristics of two different Bipolar Junction Transistors (BJT), BJT $1$ with magnitude of Early voltage $\left|V_{A 1}\right|$, and BJT $2$ with magnitude of Early voltage $\left|V_{A 2}\right|$. Which of the following options is/are correct regarding the Early voltages?

A small signal source, $V_{i}(t)=A \cos \left(10^{5} t\right)+B \sin \left(10^{7} t\right)$ is applied to a BJT circuit as shown in the Figure. Assume zero source resistance, $V_{B E}=0.7 \mathrm{~V}, \beta_{d c}=99$, Early voltage $=100 \mathrm{~V}$ and Thermal voltage $=25 \mathrm{mV}$. Effect of internal parasitic capacitances of the BJT may be …

Consider an LED based on a direct bandgap semiconductor material with energy bandgap $1.3$ eV. Given: Plank's constant, $h=6.63 \times 10^{-34} \mathrm{~J} \mathrm{~s}$ and speed of light in free space is $3 \times 10^{8} \mathrm{~m} \mathrm{~s}^{-1}$. In which of the following wavelength ranges the LED will NOT emit?