First please remember that jamming or causing interference to other spectrum users is legally prohibited and punished.
Second, technically, you can build a noise generator with an avalanche diode, then add a wideband amplifier with a desired gain to generate a wideband noise power.
Check "www.noisecom.com", they make "amplified noise modules" with a high noise output. On how to make a diode noise generator, check ARRL Radio amateur's handbook.
I made many microwave noise sources with avalanche diodes but never intended to jam anyone. I rather generate noise fields in a laboratory, to test moving objects for loss and reflectivity.