Lasing from ZnO nanorods on ITO-coated substrates

Abstract

Lasing was observed from ZnO nanorods prepared by a simple method of chemical bath deposition (CBD) on ITOcoated glass substrates. The X-ray diffraction pattern showed a dominant peak for (002) plane typical for good crystalline quality of ZnO grown in the z-direction with a wurtzite structure. Continuous-wave photoluminescence (PL) spectra revealed a peak centered at 380 nm corresponding to the band gap of ZnO. Under pulsed optical pumping, lasing was observed above the nominal PL peak, initially for one mode at 384 nm. Two additional modes at 386 nm and 390 nm was observed when the pumping power is further increased. Threshold was achieved at 0.7 μJ which was 10 times smaller than that reported for powder-based random lasers. In addition, gain pinning was also observed for the dominant mode and the additional two modes appeared upon onset of this gain pining behavior.