Avalanche photodiode

A structure, comprising:

• a semiconductor material;
• a trench formed in the semiconductor material, the trench having sidewalls and a bottom;
• a semiconductor material having a first dopant type which lines the sidewalls and the bottom of the trench;
• an intrinsic photosensitive semiconductor material contacting the semiconductor material;
• a second semiconductor material having the first dopant type and which is in the trench and contacting the intrinsic photosensitive semiconductor material;
• and
• an isolation structure comprising reflective material surrounding the trench, and remotely positioned from the intrinsic photosensitive semiconductor material.

A method comprising:

• forming a trench in a substrate;
• providing a liner of semiconductor material on sidewalls and a bottom of the trench;
• forming an undoped photosensitive material on the semiconductor material within the trench;
• forming another semiconductor material on the undoped photosensitive material, within an outside of the trench;
• and
• forming trench structures with reflective material in the substrate adjacent to the liner of the semiconductor material.