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D/A conversion Semiconductors The density of carriers in a semiconductor

D/A conversion Semiconductors The density of carriers in a semiconductor For silicon at room temperature: Drift current density: j = Qv , Q - charge density, v - velocity of charge in an electric field

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D/A conversion Semiconductors The density of carriers in a semiconductor

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  1. D/A conversion Semiconductors The density of carriers in a semiconductor For silicon at room temperature: Drift current density: j = Qv, Q - charge density, v - velocity of charge in an electric field jTdrift =jn + jp = q(n n + p p)E = E,  = q(n n + p p) (cm)-1 ,  = 1/ (cm) Charge neutrality q(ND + p - NA - n) = 0; in thermal equilibrium: pn = ni2 For n-type: . If (ND - NA) >> 2ni, n (ND - NA) Similarly for p-type. Diffusion current , VT =kT/q, is approximately 25 mV,

  2. Total current • or

  3. pn-junction and Diodes For reverse bias: - diode equation. where IS = reverse saturation current (A) vD = voltage applied to diode (V)q = electronic charge (1.60 x 10-19 C)k = Boltzmann’s constant (1.38 x 10-23 J/K)T = absolute temperaturen = nonideality factor (dimensionless)VT = kT/q = thermal voltage (V) (25 mV at room temp.) ISis typically between 10-18 and 10-9 A, and is strongly temperature dependent due to its dependence on ni2. The nonideality factor is typically close to 1

  4. Rectifiers Half-wave Full wave

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