Avalanche photodiodes and methods of fabricating the same

A method of fabricating an avalanche photodiode, comprising:

• forming a compound semiconductor absorption layer, a compound semiconductor grading layer, a charge sheet layer, a compound semiconductor
• amplification layer, a selective wet etch layer, and a p-type conductive layer on an n-type substrate, wherein the compound semiconductor absorption layer, the compound semiconductor grading layer, the charge sheet layer, the compound semiconductor amplification layer, the selective wet etch layer, and the p-type conductive layer are sequentially formed on the n-type substrate through a metal organic chemical vapor deposition process;
• forming a p-type conductive mesa pattern by performing a plasma dry etch process on the p-type conductive layer;
• and
• forming an undercut region and a selective wet etch layer aperture pattern under the p-type conductive mesa pattern by performing a wet etch process on the selective wet etch layer by using the p-type conductive mesa pattern as an etch mask.