Question

Determine the diode current at 20 c for a silicon diode with is=50na with an applied forward voltage 0.6v'

Answer 1

20 c for a silicon diode with is=50na with an applied forward voltage 0.6v'

Answer 2

Concept:

Shockley equation will be used to solve this question.

Given:

Current = 50 × 10⁻⁹ A

Temperature = 20°C or 293 K

Voltage = 0.6 Volt

Silicon Diode so n = 2

Find:

Diode current

Solution:

Shockley equation is for  P-N junction or diode.

Id = Is ( ( e ^ (qVd/nKT) ) - 1 )

Where Is is the reverse saturation current

q is charge on electron

Vd is applied voltage

n is ideality factor

K is Boltzmann's constant

T is temperature in kelvin

for silicon diode ideality factor (n) = 2

charge on electron = 1.6 × 10⁻¹⁹ coulombs

Boltzmann's constant = 1.38 × 10⁻²³ m² kg s⁻² K⁻¹

Putting everything in equation

Id = Is ( ( e ^ (qVd/nKT) ) - 1 )

Id = 50 × 10⁻⁹ ( ( e ^ ((1.6 × 10⁻¹⁹)×0.6/2×(1.38 × 10⁻²³)×293) ) - 1 )

Id = 50 × 10⁻⁹ ( ( e ^ ((0.96 × 10⁻¹⁹)/(808.68 × 10⁻²³) ) - 1 )

Id = 50 × 10⁻⁹ ( ( e ^ 11.87 ) - 1 )

Id = 50 × 10⁻⁹ ( ( 142914.2387) - 1 )

Id = 50 × 10⁻⁹ × ( 142913.2387 )

Id = 7145662 × 10⁻⁹

Id = 7.145662 × 10⁻³ Ampere

Id = 7.15 × 10⁻³ Ampere (approximately) or 7.15 mA (approximately)

Hence, The diode current will be 7.15 mA (approximately).

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