Electrically pumped wavelength-tunable ultraviolet random lasing from MgxZn1-xO films on Si

We report the electrically pumped wavelength-tunable ultraviolet random lasing from MgxZn1-xO films with different bandgap energies, which act as the semiconductor components in metal-insulator-semiconductor (MIS) structures fabricated on Si substrates. When the metal (Au herein) gates of the MIS structures are applied with sufficiently high positive voltages, random lasing from the MgxZn1-xO films occurs, featuring a series of narrow spikes in the emitted spectra. Overall, the central wavelength of the random lasing spectrum is tuned from similar to 377 to 352 nm with the increase of x value in MgxZn1-xO from 0 to 0.35. The mechanism for the electrically pumped random lasing has been tentatively elucidated taking into account both the multiple optical scattering and the optical gain proceeding in the MgxZn1-xO films. (C) 2010 Optical Society of America