High Electron Mobility Transistor and Method of Forming the Same

A High Electron Mobility Transistor (HEMT) comprising:

• a gallium nitride (GaN) layer;
• an indium gallium nitride (InGaN) layer over and contacting the GaN layer;
• an aluminum gallium nitride (AlGaN) layer over and contacting the InGaN layer;
• a dielectric passivation layer over the AlGaN layer;
• a gate electrode over the AlGaN layer;
• and
• a source region and a drain region over the AlGaN layer, wherein the source region and the drain region are on opposite sides of the gate electrode, and wherein the source region and the drain region penetrate through the dielectric passivation layer to contact the AlGaN layer.

A method of forming a High Electron Mobility Transistor (HEMT), the method comprising:

• epitaxially growing a first III-V compound layer having a first band gap;
• epitaxially growing a second III-V compound layer having a second band gap smaller than the first band gap over the first III-V compound layer;
• epitaxially growing a third III-V compound layer having a third band gap greater than the first band gap over the second III-V compound layer;
• forming a gate electrode over the III-V compound layer;
• and
• forming a source region and a drain region over the third III-V compound layer and on opposite sides of the gate electrode.