Reverse-bias-driven whispering gallery mode lasing from individual ZnO microwire/p-Si heterojunction

In this paper, electrically driven whispering gallery mode (WGM) lasing was observed from ZnO single microwire (SMW)/p-Si heterojunctions operated at reverse bias. Current–voltage curve exhibits a non-ideal rectification characteristic with a turn-on voltage of about 0.8 V. When the reverse current of 20 mA was applied, several sharp lasing peaks with FWHM as narrow as ∼2 nm appeared in the spectra, which demonstrated that the gain was now large enough to enable the cavity resonant in ZnO SMW. The resonant process, lasing mode and quality factor (Q) were investigated via experiments and theory. The observed discrete lasing peak positions effectively matched the simulated lasing modes. The carrier transport process and light emission mechanism in heterojunctions are also discussed by energy band theory and interface defect.