We report on manipulating the stimulated emission of monolayer molybdenum disulfide （MoS2） with the piezoelectric effect. The analysis is based on quantum mechanics. The stimulated emission of this two-dimensional m...We report on manipulating the stimulated emission of monolayer molybdenum disulfide （MoS2） with the piezoelectric effect. The analysis is based on quantum mechanics. The stimulated emission of this two-dimensional material has been simulated to establish the relation between the total emission rate and the energy of the photon excitation. We demonstrate that the piezoelectric-induced charges enhance the emission rate by changing the carrier concentration. It is found that the emission intensity is proportional to the carrier density in the low-density range, and eventually reaches a steady value in the high-density region. An externally applied mechanical force also leads to a change in the second harmonic generation of the monolayer MoS2.展开更多
NO_2 sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However,traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here...NO_2 sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However,traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here, we report a simply and reliable flexible NO_2 sensor based on single-layer MoS_2. The flexible sensor exhibits high sensitivity to NO_2 gas due to ultra-large specific surface area and the nature of two-dimensional(2 D) semiconductor. When the NO_2 is 400 ppb(parts per billion), compared with the dark and strain-free conditions, the sensitivity of the single-layer sensor is enhanced to 671% with a625 nm red light-emitting diode(LED) illumination of 4 mW/cm^2 power under 0.67% tensile strain.More important, the response time is dramatically reduced to $16 s and it only needs $65 s to complete90% recovery. A theoretical model is proposed to discuss the microscopic mechanisms. We find that the remarkable sensing characteristics are the result of coupling among piezoelectricity, photoelectricity and adsorption-desorption induced charges transfer in the single-layer MoS_2 Schottky junction based device.Our work opens up the way to further enhancements in the sensitivity of gas sensor based on single-layer MoS_2 by introducing photogating and piezo-phototronic effects in mesoscopic systems.展开更多
文摘We report on manipulating the stimulated emission of monolayer molybdenum disulfide （MoS2） with the piezoelectric effect. The analysis is based on quantum mechanics. The stimulated emission of this two-dimensional material has been simulated to establish the relation between the total emission rate and the energy of the photon excitation. We demonstrate that the piezoelectric-induced charges enhance the emission rate by changing the carrier concentration. It is found that the emission intensity is proportional to the carrier density in the low-density range, and eventually reaches a steady value in the high-density region. An externally applied mechanical force also leads to a change in the second harmonic generation of the monolayer MoS2.
基金supported by the National Key Research and Development Program of China(2016YFA0202703,2016YFA0202704)the National Natural Science Foundation of China(51472056)+1 种基金the Thousands Talents Plan For Pioneer Researcher And His Innovation Team,Chinathe Recruitment Program of Global Youth Experts,China
文摘NO_2 sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However,traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here, we report a simply and reliable flexible NO_2 sensor based on single-layer MoS_2. The flexible sensor exhibits high sensitivity to NO_2 gas due to ultra-large specific surface area and the nature of two-dimensional(2 D) semiconductor. When the NO_2 is 400 ppb(parts per billion), compared with the dark and strain-free conditions, the sensitivity of the single-layer sensor is enhanced to 671% with a625 nm red light-emitting diode(LED) illumination of 4 mW/cm^2 power under 0.67% tensile strain.More important, the response time is dramatically reduced to $16 s and it only needs $65 s to complete90% recovery. A theoretical model is proposed to discuss the microscopic mechanisms. We find that the remarkable sensing characteristics are the result of coupling among piezoelectricity, photoelectricity and adsorption-desorption induced charges transfer in the single-layer MoS_2 Schottky junction based device.Our work opens up the way to further enhancements in the sensitivity of gas sensor based on single-layer MoS_2 by introducing photogating and piezo-phototronic effects in mesoscopic systems.
