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 similar to2 mum is confirmed, and material properties are improved by adjusting the growth conditions and buffer layer structural design. (C) 2002 Elsevier Science B.V. All rights reserved.