Method of forming a high electron mobility transistor

A method of forming a high electron mobility transistor (HEMT), the method comprising:

• selectively implanting p-type dopants into a first III-V compound layer through a second III-V compound layer disposed over the first III-V compound layer;
• selectively implanting n-type dopants into the second III-V compound layer and the first III-V compound layer;
• annealing implanted p-type dopants and n-type dopants in the second III-V compound layer and the first III-V compound layer;
• forming a source feature and a drain feature on the second III-V compound layer;
• and
• forming a gate electrode over the second III-V compound layer between the source feature and the drain feature.

A method of forming a high electron mobility transistor (HEMT), the method comprising:

• forming a gallium nitride (GaN) layer on a substrate;
• forming an aluminum gallium nitride (AlGaN) layer on the GaN layer;
• forming a source feature and a drain feature spaced apart from each other and on the AlGaN layer;
• forming an n-type doped region underlying each source feature and drain feature in the AlGaN layer;
• forming a p-type doped region underlying each n-type doped region in the GaN layer;
• and
• forming a gate electrode over a portion of the AlGaN layer between the source feature and the drain feature.