Test: P-i-n Diode & Its Characteristics - Electrical Engineering (EE) MCQ

 An intrinsic layer that is sandwiched between p and n layers. This gives a larger surface area making it compatible for photosensitivity. Reverse bias causes an increased depleted region in a PIN diode.

In forward bias, the forward resistance decreases and acts as a variable resistor. The low frequency model of a PIN diode neglects the input capacitive values.

In reverse bias, the intrinsic layer is completely covered by depletion layer. The stored charges vanishes acting like a variable capacitor. The high frequency model of a PIN diode neglects the input resistances.

When p region is used for high resistance, the depletion layer is high at p side.When n side is used the depletion layer is high at n side. They are called as π and ϒ regions respectively.

Being employed at 300Hz, the swept voltage is attained at π region.Then it’s used as a microwave switch. Swept voltage is nothing but, the voltage at which the complete intrinsic layer is swept out as a depleted one.

 At high frequency, the applied values for resistance and capacitance is 0.1 to 10KΩ and 0.02 to 2pF respectively. At high frequencies, it almost acts as a perfect resistor.

In a low frequency model, the resistance decreases and reactance increases.Here the variable resistance is neglected. At low frequencies, the charge can be removed and the diode can be turned off.

Due to increased depletion region, the covalent bonds break and increase the surface area for photosensitivity. This property is used in fields of light sensors, image scanners, artificial retina systems.

The forward current depends on mobility and carrier concentration. In frequency models, the value of forward current is IF = A*(µ_PP + µ_NN)q. Where, µ_P and µ_Nare the mobility of p and n type charge carriers respectively.

Forward resistance for a PIN diode depends on the width, current density and positive carrier concentration of the diode. No diode is perfectly ideal. In practise, a diode offers a small resistance in forward bias which is called as forward resistance.