Schottky Junction

In a P-N junction, conduction involves injection of both carrier types across the junction, which on turn-off requires clearing out accumulated minority carriers (reverse recovery time). In a Schottky diode, current is carried only by majority carriers (between metal and semiconductor), so it switches off far faster.

The saturation current density $J_S=A^*T^2 e^{-q\varphi_B/kT}$ depends on the barrier height, which is typically (0.5-0.9 eV) much lower than the effective barrier of a silicon P-N junction — giving a 3-5x lower turn-on voltage for the same current.

$1/C^2 = \frac{2(V_{bi}-V)}{q\varepsilon N_d}$ is linear in $V$. The slope directly gives $N_d$, and the intercept on the $V$-axis gives $V_{bi}$. This is a standard experimental technique for measuring doping and built-in potential from capacitance measurements.

The low forward voltage (less rectification loss) and near-zero reverse recovery time (majority carriers only) make the Schottky diode ideal for switching power supplies, RF rectifiers, and high-speed logic clamping (e.g. preventing transistor saturation).