Enhanced Light Extraction from Gallium Nitride Optoelectronics on Si Substrates

This letter presents a technique to enhance the light extraction from a III-nitride light emitting diode on a Si substrate by inserting a high-reflectance distributed Bragg reflector below the active layer of the device to reflect the emitted light away from the opaque substrate. Additionally, the alternating layer sequence in the distributed Bragg reflector absorbs strain and filters dislocations generated at the GaN / Si interface. Theoretical results show that optimal placement of the light source is critical to achieve enhanced emission from the optical cavity.