Optical and structural properties of GaN materials and structures 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 (001) substrates with specially designed composite intermediate layers consisting of an ultra-thin amorphous Si layer and a GaN/AlGaN multilayered buffer by low pressure metalorganic chemical vapor deposition. Their optical and structural properties were studied by a variety of characterization techniques, including X-ray diffraction (XRD), Raman scattering, Fourier transform infrared reflectance, photoluminescence, scanning and transmission electron microscopy. Wurtzite GaN structure with the single crystalline grain size up to ∼2 μm is confirmed, and material properties are improved by adjusting the growth conditions and buffer layer structural design.