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Structural and optical properties of GaN materials grown on Si by metalorganic chemical vapor deposition

GaN thin films, undoped, Si- and Mg-doped, and InGaN-GaN multiple quantum well (MQW) structures have been grown on Si substrates with specially designed composite intermediate layers consisting of a ultra-thin amorphous Si layer and a GaN/AlGaN multilayered buffer by low pressure metalorganic chemical vapor deposition. The structural and optical properties of these new grown material were studied. X-ray diffraction, Raman scattering and Fourier transform IR reflectance measurement confirmed their wurtzite structure. Scanning electron microscopy exhibited the single crystalline grain size up to approximately 2 micrometers . Photoluminescence showed strong GaN near edge emission, with only very weak deep defect-related emissions, for GaN films, and strong MQW emissions. The film surface morphology and material properties are improved by adjusting the growth conditions and buffer layer structural design.