UV random lasing action in p-SiC(4H)/i-ZnO-SiO₂ nanocomposite/n-ZnO: Al heterojunction diodes

The ultraviolet (UV) lasing action in p-SiC(4H)/i-ZnO-SiO2 nanocomposite/n-ZnO:Al heterojunction diodes was investigated. A p-doped single-side-polished 4H-SiC substrate was used as the hole-injection layer and an n-doped ZnO:Al layer of thickness ca.250 nm was used as the electron-injection layer. It was observed that ZnO clusters, which cause the formation of a corrugated surface on the diodes, are enclosed inside the SiO2 matrix. At low excitation intensity, the FWHM and peak wavelength of the UV spectrum were ca. 17.4 and ca. 383 nm, respectively. The peak wavelength of the diodes under electrical excitation was stationary at ca. 383 nm, while than under optical excitation is red-shifted from ca. 383 to ca. 386 nm.