Why the diode shows a loop in the I_V characteristics?(Diode part N4003, Frequency was 100k) My instructor told me something regrading the retardation of charge carriers but I couldn't understand/find anything.Will someone please explain it to me? 
Electronic – Deviation from typical I-V characteristics of a diode in high frequency
diodespn-junction
Related Solutions
Both diodes work the same way by allowing current to flow in one direction. The differences have to do with power and frequency characteristics. They are made from a p-n junction and are two lead devices.
Small signal diodes have much lower power and current ratings, around 150mA, 500mW maximum compared to rectifier diodes, they can also function better in high frequency applications or in clipping and switching applications with short-duration pulse waveforms.
Rectifier diodes are designed to handle much higher voltage and current and are typically found in power supplies.
As far as the Lissajous patterns look like, they can be modeled in practically any simulation software. Check out LTSpice from Linear Technologies. http://www.linear.com/designtools/software/ . Plenty of tutorials and a large model library.
As the injected minority carriers recombine, they have to recombine with something. What they recombine with is some of the majority carriers. So majority carriers near the junction are being "used up" by the recombination process.
As the majority carriers are taken up by recombination, new majority carriers flow in from the area farther away from the junction. This majority carrier flow is what carries the current in the "far away" part of the device.
I found a diagram showing this here:
Best Answer
Reverse recovery time quote from Wiki: -
This is why some diodes are useless for switching circuits or power supplies or for radio frequency applications. Some versions of the 1N400x diode can have reverse recovery times of 30 us: -