Questions & Answers of Generation and Recombination of Carriers

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 1X1015 cm-3, respectively. The lifetimes of electrons in P region and holes in N region are both 100 μs. The electron and hole diffusion coefficients are 49 cm2/s and 36 cm2/s, respectively. Assume kT/q = 26m V , 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

A p+n junction has a built-in potential of 0.8 V. The depletion layer width at a reverse bias of 1.2V is 2µm. For a reverse bias of 7.2 V, the depletion layer width will be

Group I lists four types of p-n junction diodes. Match each device in Group I with one of the option in Group II to indicate the bias condition of that device in its normal mode of operation.

 Group I Group II
P. Zener Diode 1. Forward bias
Q. Solar cell 2. Reverse bias
R. LASER diode  
S. Avalanche Photodiode