Electronic Devi...

The probability that an energy state is filled at E_C + KT, is equal to the probability that a state is empty at E_C + KT. Where is the Fermi level (E_F) located?

Assume that gallium arsenide has dopant concentrations of N_d = 1 × 10¹³ cm^-3 and N_a = 2.5 × 10¹³ cm^-3 at T = 300 K. Assuming that the concentration of donor ‘or’ acceptor is ≫ n_i, the material is

A n-type Si sample is uniformly doped with 10¹⁵ donors per cm³ and has minority carriers lifetime τ_p = 10^-6sec. The photo generation rate that will produce 2 × 10¹³ excess pairs cm^-3 in steady state is _________ × 10¹⁹ eh – pair/sec

A solar cell has a short circuit current of 10 mA and open-circuit voltage of 0.9 V. The maximum power delivered by the solar cell is _________ mW. Given fill factor as 0.8.

If the substrate doping concentration is decreased, the accumulation region capacitance and depletion region capacitance respectively will

Growth of SiO₂ on Si subtrate can be achieved in 2 ways either using oxygen or using water vapour. For growing thicker oxides

Consider the uniformly doped GaAs junction at T = 300 K. At zero bias, only 20 percent of the total space charge region is to be in the p region. The built-in potential barrier for an intrinsic concentration of n_i = 1.8 × 10⁶ cm^-3 is V_bi = 1.20 V. The thermal voltage at T = 300 K is 25.9 mV and the relative permittivity ε_r = 13.1, ε₀ = 8.85 × 10^-14 Farad-cm.

A Ga – As LED has refractive index of 3.6 and is surrounded by air (μ = 1). If the bandgap of Ga – As is 1.43. Then out of 500 photons generated in Ga – As, The number of photons emitted out of the specimen are _____

The change in diode voltage that will cause a factor of 50 increase in current for an ideal pn junction diode at T = 300 K operating in the forward-bias region is approximately:

 $(Take{V}_T=\frac{kT}{q}=25mV)$ 

A MOSFET with VDS = 0.5 V carries a drain current of 1 mA in saturation. If channel length modulation parameters λ = 0.2 V^-1  then the drain current if VDS is 1 V is:

Consider a uniformly doped silicon bipolar transistor with a metallurgical base width of 0.5 μm and a base doping of N_B = 10¹⁶ cm^-3. The punch-through voltage V_pt is given as V_pt = 25 V with Punch through voltage defined as the base-collector voltage responsible for B-C depletion region to penetrate completely through the base. The collector doping concentration to meet the given punch-through voltage is (up to 2 decimal places) _____________× 10¹⁴ cm^-3.(Take ϵ_r = 11.7)

(Assume bias voltage at collector-base junction is very large as compared to built-in voltage at base-collector region)

Excess carriers have been generated uniformly in a semiconductor to a concentration of δn(0) = 10¹⁵ cm^-3 (δn(0) represents the excess carrier concentration at t = 0). The forcing function generating the excess carriers turns off at time t = 0. If the excess carrier lifetime is τ_no = 10^-6sec, the excess carrier concentration at t = 10μs is: