# Questions & Answers of Generation and Recombination of Carriers

## Weightage of Generation and Recombination of Carriers

Total 11 Questions have been asked from Generation and Recombination of Carriers topic of Electronic Devices subject in previous GATE papers. Average marks 1.64.

A region of negative differential resistance is observed in the current voltage characteristics of a silicon PN junction if

The built-in potential of an abrupt p-n junction is 0.75 V. If its junction capacitance (CJ) at a reverse bias (VR) of 1.25 V is 5 pF, the value of CJ (in pF) when VR = 7.25 V is_________.

For a silicon diode with long P and N regions, the accepter and donor impurity concentrations are 1 x 1017 cm-3 and 1 x 1015 cm-3, respectively. The lifetimes of electrons in P region and holes in N region are both 100 $\mathrm{\mu }$s. The electron and hole diffusion coefficients are 49 cm2/s and 36 cm2/s, respectively. Assume kT/q = 26 mV , the intrinsic carrier concentration is 1 X 1010 cm-3, and q = 1.6 X 10-19 C. When a forward voltage of 208 mV is applied across the diode, the hole current density (in nA/cm2) injected from P region to N region is _________.

The electric field profile in the depletion region of a p-n junction in equilibrium is shown in the figure. Which one of the following statements is NOT TRUE?

A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10oC, the forward bias voltage across the PN junction

Compared to a p-n junction with NA=ND=1014/cm3, which one of the following statements is TRUE for a p-n junction with NA=ND=1020/cm3?

Which of the following is NOT associated with a p-n junction?

Consider the following assertions
S1: For Zener effect to occur, a very abrupt junction is required
S2: For quantum tunneling to occur, a very narrow energy barrier is required
Which of the following is correct?

In a p+n junction diode under reverse bias, the magnitude of electric field is maximum at