Ultraviolet random lasing from asymmetrically contacted MgZnO metal-semiconductor-metal device

Abstract

Nitrogen-doped Mg0.12Zn0.88O nanocrystalline thin film was grown on c-plane sapphire substrate. Asymmetric Ni/Au and Ti/Au Schottky contacts and symmetric Ni/Au contacts were deposited on the thin film to form metal-semiconductor-metal (MSM) laser devices. Current-voltage, photocurrent, and electroluminescence characterizations were performed. Evident random lasing with a threshold current of ∼36 mA is demonstrated only from the asymmetric MSM device. Random lasing peaks are mostly distributed between 340 and 360 nm and an output power of 15 nW is measured at 43 mA injection current. The electron affinity difference between the contact metal and Mg0.12Zn0.88O:N layer plays an important role for electron and hole injection and subsequent stimulated random lasing.