A lithium and nitrogen codoping method has been employed to prepare p-type MgZnO films, and p-MgZnO/i-ZnO/n-ZnO structured light-emitting devices (LEDs) and photodetectors have been fabricated. The LEDs can work continuously for about 97 h under the injection of a 20 mA continuous current, which is the best value ever reported for ZnO-based LEDs. The performance of the photodetectors degrades little after several running cycles. The above results reveal the applicability of the p-MgZnO films in optoelectronic devices.

In this letter, we present a Michelson interferometer for the hyperfine spectrum measurement of an optically pumped far-infrared laser with a highest frequency resolution of 3-5 GHz. CH 3 OH gas with a purity of 99.9%, is pumped by the CO 2 9P36 and 9R10 laser lines to generate terahertz lasers with frequencies of 2.52 and 3.11 THz, respectively. Moreover, except for the center frequency, which is in good agreement with theoretical work, some additional frequencies on both sides of the center frequency are obtained at a frequency interval of 0.15 THz. Meanwhile, the mechanism behind the observed experimental results is also investigated.