[Amps] small signal diodes

[Dan Sawyer]

All,

I have been repairing an 8405a and have noticed something about the 
probe sampling diodes. The HP sampling diodes have a peculiar curve that 
other diodes do not seem to have. They have a very sharp 'knee' and a 
very steep rise. Other diodes do not have that sharp knee or near 
vertical rise. In looking for a replacement, what type of diodes would 
have this characteristic?

Thanks,

Dan