Hyphenation is probably one of the most overlooked aspects of good writing. Grammarly has a useful guide.

One of the rules mentioned in the guide governs the combination of an adverb and a past participle, e.g., “forward biased”.

• When “forward biased” is used before a noun, it should be “forward-biased”, e.g., “a forward-biased diode”. Without the hyphen, “a forward biased diode” could be mistaken as a “biased diode” that is “forward”.
• When “forward biased” is used after a noun, it should be written as is, e.g., “the diode is forward biased”.