Unterschied Charge carrier life time und Reverse Recovery time

[lutz (Gast)]

Hallo,

ich habe mir gerade das Datenblatt der Bas70 angeschaut und wollte die 
reverse recovery time wissen.
nun bin ich aber auf die charge recovery time gestoßen. Ist das nicht 
dasselbe ?
http://www.infineon.com/dgdl/Infineon-BAS70_BAS170SERIES-DS-v01_01-en.pdf?fileId=db3a304314dca389011518ad41680e12

[Hp M. (nachtmix)]

lutz schrieb:
> nun bin ich aber auf die charge recovery time gestoßen.

Was du nicht alles findest...

[Marcus H. (Firma: www.harerod.de) (lungfish)]

Interessante Frage, schau mal andere Datenblätter an:
https://www.vishay.com/docs/85702/bas70.pdf

Im Tietze Schenk wird die Diodenkapazität abhängig von der Transitzeit 
angeben, bei Schottky-Dioden bei typischerweise  bis zu 100ps liegt. 
Daraus wiederum ergibt sich die Erholzeit.
Ich möchte aber Transitzeit und Rekombinationszeit nicht vermischen.

Das o.g. Vishay Datenblatt gibt die Erholzeit mit 5ns an:
ReVerSe recovery time
IF = IR = 10 mA
iR = 1 mA,
RL = 100 
trr 5 ns

Mal schauen, ob der gute Lothar Miller was weiß...

[Lutz (Gast)]

Marcus H. schrieb:
> Interessante Frage, schau mal andere Datenblätter an:
> https://www.vishay.com/docs/85702/bas70.pdf
>
> Im Tietze Schenk wird die Diodenkapazität abhängig von der Transitzeit
> angeben, bei Schottky-Dioden bei typischerweise  bis zu 100ps liegt.
> Daraus wiederum ergibt sich die Erholzeit.
> Ich möchte aber Transitzeit und Rekombinationszeit nicht vermischen.
>
> Das o.g. Vishay Datenblatt gibt die Erholzeit mit 5ns an:
> ReVerSe recovery time
> IF = IR = 10 mA
> iR = 1 mA,
> RL = 100 
> trr 5 ns
>
> Mal schauen, ob der gute Lothar Miller was weiß...

Soweit so gut, aber noch habe ich den unterschied nicht ganz 
verstanden..

hier noch ein Kommentar von

https://electronics.stackexchange.com/questions/13912/what-is-the-reverse-recovery-time-in-diode

"If a diode is conducting in a forward condition and immediately 
switched to a reverse condition, the diode will conduct in a reverse 
condition for a short time as the forward voltage bleeds off. The 
current through the diode will be fairly large in a reverse direction 
during this small recovery time.

After the carriers have been flushed and the diode is acting as a normal 
blocking device in the reversed condition, the current flow should drop 
to leakage levels.

This is just a generic description reverse recovery time. It can affect 
quite a few things, depending on context, as mentioned in the comments."

[Marcus H. (Firma: www.harerod.de) (lungfish)]

Guter Link, mit guten Antworten.
Ich sehe da im Moment zwei Effekte:
- Transitzeit von Ladungsträgern durch die Sperrschicht
- Rekombinationszeit, bis freie Elektronen die Löcher wieder aufgefüllt 
haben

Bisher kannte ich nur die Transitzeit aus dem TS.

- - - -
compumike schrieb:
 space charge within a P-N junction needs to be established before 
forward current can flow. (If the first sentence makes you ask why, 
that's really a separate question -- perhaps this can help. Let's just 
look at the dynamics of establishing and neutralizing that space 
charge.)

From zero, this space charge can be established quite quickly, because 
an externally applied forward bias voltage can route electrons 
externally around. Electrons diffuse from the n-type material into the 
edge of the p-type material, holes in the p-type material diffuse into 
the edge of the n-type material, and at the metal interfaces, new 
electrons are injected into the n-type end and holes are generated at 
the p-type end to produce free electrons that can flow in the external 
circuit. All of these flows are flows of majority carriers in their 
respective materials, so diffusion happens quickly driven by much larger 
concentration gradients. A space charge develops rapidly because 
majority carriers are flowing to turn the diode on -- electrons in the 
n-type material, and holes in the p-type material.

However, if the external voltage is then reversed to be a reverse bias, 
the space charge is attracted to itself to recombine. But this 
recombination only happens through the diffusion of minority carriers. 
This minority carrier diffusion has much smaller concentration 
gradients, and therefore diffuses orders of magnitude more slowly. An 
external circuit providing reverse bias can aid in speeding this 
recombination, as it can allow for faster neutralization of excess holes 
that migrated back to the p-type material, and removal of excess 
electrons that migrated back to the n-type material. This hole-electron 
recombination or charge neutralization is assumed to happen essentially 
instantaneously at the semiconductor-metal interfaces, so if the 
external current can supply and remove electrons under reverse bias, it 
will do so much faster than the "normal" hole-electron recombination 
rate in the bulk of the semiconductor. That's why there can be huge 
reverse currents during the reverse recovery time.