GATE EC 2017 Question Paper (05-Feb-2017) (Shift 2)

A MOS capacitor is fabricated on p-type Si (Silicon) where the metal work function is 4.1 eV and electron affinity of Si is 4.0 eV. E${}_C$ - E${}_F$ = 0.9 eV, where E${}_C$ and E${}_F$ are the conduction band minimum and the Fermi energy levels of Si, respectively. Oxide ϵᵣ = 3.9, ϵₒ = 8.85 × 10⁻¹⁴ F/cm, oxide thickness tₒₓ = 0.1 μm and electronic charge q = 1.6 × 10⁻¹⁹ C. If the measured flat band voltage of this capacitor is -1 V, then the magnitude of the fixed charge at the oxide-semiconductor interface, in nC/cm², is ________.

For a particular intensity of incident light on a silicon p-n junction solar cell, the photocurrent density (J${}_L$) is 2.5 mA/cm² and the open-circuit voltage (V${}_{oc}$) is 0.451 V. Consider thermal voltage (V${}_T$) to be 25 mV. If the intensity of the incident light is increased by 20 times, assuming that the temperature remains unchanged, V${}_{oc}$ (in volts) will be ___________.

(Take the ideality factor, η = 2 for Silicon)

Two n-channel MOSFETs, T1 and T2, are identical in all respects except that the width of T2 is double that of T1. Both the transistors are biased in the saturation region of operation, but the gate overdrive voltage (V${}_{GS}$ - V${}_{TH}$) of T2 is double that of T1, where V${}_{GS}$ and V${}_{TH}$ are the gate-to-source voltage and threshold voltage of the transistors, respectively. If the drain current and transconductance of T1 are I${}_{D1}$ and g${}_{m1}$ respectively, the corresponding values of these two parameters for T2 are

An abrupt p-n junction (located at x = 0) is uniformly doped on both p and n sides. The width of the depletion region is W and the electric field variation in the x-direction is E(x). Which of the following figures represents the electric field profile near the p-n junction?

Assuming that transistors M₁ and M₂ are identical and have a threshold voltage of 1 V, the state of transistors M₁ and M₂ are respectively