Light-emitting diodes with buffer layers

A method of fabricating a semiconductor device, comprising:

• forming a buffer layer by alternatingly depositing a plurality of semiconductor material layers and a plurality of oxygen-doped material layers on a substrate;
• and
• disposing an epitaxial layer above the buffer layer;
• wherein oxygen concentrations of the oxygen-doped material layers gradually decrease along a direction from the substrate to the epitaxial layer.

A light-emitting diode (LED) chip, comprising:

• a sapphire substrate;
• a buffer layer deposited on the sapphire substrate, the buffer layer including a plurality of aluminum nitride (AlN) layers and a plurality of oxygen-containing AlN layers, the AlN material layers and the oxygen-containing AlN layers deposited in an alternating arrangement on top of each other;
• and
• an epitaxial layer includes gallium nitride (GaN) above the buffer layer.