GATE EC 2020 Question Paper (02-Feb-2020) (Shift 2)

A one-sided abrupt pn junction diode has a depletion capacitance C${}_D$ of 50 pF at a reverse bias of 0.2 V. The plot of $\frac{1}{C_D^2}$ versus the applied voltage V for this diode is a straight line as shown in the figure below. The slope of the plot is ______ × 10²⁰ F⁻²V⁻¹

The band diagram of a p-type semiconductor with a band-gap of 1 eV is shown. Using this semiconductor, a MOS capacitor having V${}_{TH}$ of -0.16 V, $C_{ox}^{\prime }$ of 100 nF/cm${}^{2,}$ and a metal function of 3.87 eV is fabricated. There is no charge within the oxide. If the voltage across the capacitor is V${}_{TH}$, the magnitude of depletion charge per unit area (in C/cm²) is

The base of an npn BJT T1 has a linear doping profile N${}_B$ (x) as shown below.

The base of another npn BJT T2 has a uniform doping N${}_B$ of 10¹⁷ cm⁻³. All other parameters are identical for both devices. Assuming that the hole density profile is the same as that of doping, the common-emitter current gain of T1 is

A pn junction solar cell of area 1.0 cm², illuminated uniformly with 100 mW cm⁻², has the following parameters: Efficiency = 15%, open circuit voltage = 0.7 V, fill factor = 0.8, and thickness = 200 μm. The charge of an electron is 1.6 × 10⁻¹⁹ C. The average optical generation rate (in cm⁻³s⁻¹) is

For the BJT in the amplifier shown below, V${}_{BE}$ = 0.7 V, kT/q = 26 mV. Assume that BJT output resistance (r₀) is very high and the base current is negligible. The capacitors are also assumed to be short-circuited at signal frequencies. The input Vᵢ is direct coupled. The low-frequency voltage gain v₀/vᵢ of the amplifier is