Question: how zener diode is fabricated?
Answer: A Zener diode is fabricated by heavily doping both p and n sides of the junction. Because of heavy doping, a very thin (<10−6 m) depletion region is formed between the p and n sides, and hence, the electric field of the junction is extremely high (~5 × 106 V/m) even for a small reverse bias voltage of about 5V.