What electrical characteristics are specified in the diode technical datasheets?

• Reverse current (I_R) / repetitive peak reverse current (I_RRM)
  I_R and I_RRM are the leakage currents that flow in the reverse direction when a diode is reverse-biased at the specified voltage. Since the leakage currents are highly dependent on temperature, they are specified under a pulsed current condition for some diodes. Note that I_R and I_RRM are different from the maximum reverse recovery current observed during the reverse recovery process.

• Junction capacitance (C_j) / total capacitance (C_T)
  The main capacitance is the capacitance generated at the junction. There is a depletion layer at the junction, and there are almost no carriers (electrons or holes). This part corresponds to the insulation band of the capacitor. Since the width of the depletion layer is related to the magnitude of the applied reverse bias V_R, the junction capacitance is inversely related to V_R.
  In the datasheet, C_j and C_T are defined as the equivalent capacitance between the terminals when a small signal with the specified frequency is applied under the specified reverse voltage condition.

• Reverse recovery time (t_rr)
  It takes some time to bring a forward-conducting diode into a non-conducting state by applying a reverse voltage. When forward voltage is applied across a pn junction diode, electrons are injected into the n-type semiconductor (i.e., cathode side) while holes are injected into the p-type semiconductor (i.e., anode side). These majority carriers recombine near the junction or diffuse across the junction as minority carriers, causing electric current to flow.
  When reverse voltage is applied, negative current (i.e., reverse recovery current, i_rr) flows first, canceling out these majority carriers. Some of the minority carriers remaining in each layer recombine and disappear after a certain period of time (lifetime) has passed.
  Reverse recovery time (t_rr) is the time required for reverse recovery current (i_rr) to disappear. In datasheets, t_rr is specified as follows. Forward current (I_F) and its falling slew rate (di/dt) after the application of reverse voltage (V_R) are specified as test conditions. Let the time required for I_F to reach the peak value of the reverse recovery current (i_rr) value from the zero-crossing point be t1. Let the time required from the peak i_rr value to the zero-crossing point of the line passing through the 90% and 50% points of i_rr be t2. Then, reverse recovery time (t_rr) is defined as the sum of t1 and t2.
  

• Forward recovery time (t_fr)
  When a rapidly rising forward volta Even if a rapidly rising forward voltage is applied, the diode does not immediately become conductive. It takes a little time for enough carriers to be accumulated before the diode obtains high conductivity. Although the diode is forward-biased, it exhibits high resistance during this period and therefore a higher voltage than the V_F value in the conducting state. This phenomenon is called forward recovery. A diode consumes more power during the forward recovery period than it does in the steady state.
  In datasheets, t_fr is defined as the time required for forward voltage to reach its peak from 10% of V_F and then drop to 110% of V_F at the specified forward current (I_F). High-voltage diodes tend to have a long forward recovery time.
  

In addition, some diodes have individual maximum ratings. See the application note below for details.

• Basics of Diodes (Absolute Maximum Ratings and Electrical Characteristics) (PDF:1.1MB)

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