Lasing of ZnO Micro / Nanocrystals by Ultraviolet Laser Excitation and Atmospheric Alignment with Laser-induced Motions and Electrical Field

Lasing characteristics and an alignment method of ZnO micro / nanocrystals were investigated for an application to ultraviolet (UV) laser diode (LD). A single ZnO microsheet synthesized by carbothermal chemical vapor deposition method was examined by spectra observation with a thirdharmonic Nd:YAG laser ( = 355 nm, = 5 ns) as an excitation laser light. The observed emission spectra showed the lasing characteristics having mode structure and a threshold for lasing at 49 kW/cm 2 . In addition, laser-induced motions (LIM) of ZnO micro / nanocrystals at high excitation intensity beyond the lasing threshold were observed when those were excited by the UV laser beam at a repetition rate of 20 Hz. The mechanism of the LIM was discussed, and an alignment method of ZnO micro / nanocrystals using the LIM and electrical fields was demonstrated.