show mathematically that diodes obey ohm's law at low fields

Asked by neelsid | 23rd Dec, 2011, 11:59: AM

Expert Answer:

The drift velocity of a charge carrier is proportional to electric E. Therefore V = eET/m ie. V ??E But V cannot be increased indefinitely by increasing E . At high speed relaxation time (T) begins to decrease due to increase in collision frequency. S: so drift velocity saturates at thermal velocity (lOms-1). An electric field of 106 V/m causes saturation of drift velocity. Hence semi- conduction obey ohm’s law for low electrical field and above this field ( E < 106 V/m ) current becomes independent of potential

Answered by  | 26th Dec, 2011, 11:11: AM

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