MOCVD growth of GaN on Si substrates using an ALD-grown Al2O3 interlayer

Device-quality GaN thin films have been grown on Si(111) substrates using an Al 2 O 3 transition layer, and initial devices show performance similar to comparable devices on sapphire. X-ray diffraction rocking curve scans show a linewidth of 378 arcsec for the GaN (0002) reflection. Comparison of these layers to GaN layers grown on bare Si substrates shows a significant reduction in strain with the use of the Al 2 O 3 transition layer. Raman spectroscopy measurements verify this reduction in strain, as shown by the shift of the GaN E 2 (high) with variations in Al 2 O 3 layer thickness. GaN-based devices were also grown and fabricated using this process. Devices on Si showed an IQE of ∼32%, which is comparable to the -37% observed for similar devices on sapphire. The devices on Si also showed better efficiency at high current densities compared to the devices on sapphire, despite the longer peak emission wavelength on Si, which may be due to a difference in thermal conductivity between Si and sapphire. A growth process has been developed for high-quality GaN on Si, and initial device results show that Si is a viable substrate technology for MOCVD growth of GaN-based devices.