Electroluminescence from a p-type Ga As(110)surface was induced by tunneling electrons in a scanning tunneling microscope under both polarities of bias voltage.The optical spectra exhibit a polarity-independent lumine...Electroluminescence from a p-type Ga As(110)surface was induced by tunneling electrons in a scanning tunneling microscope under both polarities of bias voltage.The optical spectra exhibit a polarity-independent luminescence peak at 1.47 eV resulting from the exciton recombination.However,the quantum yield of photon emission at negative bias voltage is two orders of magnitude weaker than that at positive bias voltage.Moreover,the luminescence at negative bias voltage shows the linear dependence of bias voltage,distinct from the rapid rise due to resonant electron injection at positive bias.Furthermore,the threshold bias voltage for electroluminescence at negative bias is nearly twice the bandgap of Ga As,not simply satisfying the energy conservation for the creation of an electron–hole pair.Through theoretical calculation,we propose an impact ionization model to nicely explain the newly observed electroluminescence at negative bias voltage.We believe that this mechanism of impact ionization could be readily applied to other nanoscale optoelectronics including 2D semiconductors and 1D nanostructures.展开更多
Due to their unique characteristics,two-dimensional(2D)materials have drawn great attention as promising candidates for the next generation of integrated circuits,which generate a calculation unit with a new working m...Due to their unique characteristics,two-dimensional(2D)materials have drawn great attention as promising candidates for the next generation of integrated circuits,which generate a calculation unit with a new working mechanism,called a logic transistor.To figure out the application prospects of logic transistors,exploring the temperature dependence of logic characteristics is important.In this work,we explore the temperature effect on the electrical characteristic of a logic transistor,finding that changes in temperature cause transformation in the calculation:logical output converts from‘AND’at 10 K to‘OR’at 250 K.The transformation phenomenon of temperature regulation in logical output is caused by energy band which decreases with increasing temperature.In the experiment,the indirect band gap of MoS2 shows an obvious decrease from 1.581 eV to 1.535 eV as the temperature increases from 10 K to 250 K.The change of threshold voltage with temperature is consistent with the energy band,which confirms the theoretical analysis.Therefore,as a promising material for future integrated circuits,the demonstrated characteristic of 2D transistors suggests possible application for future functional devices.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2019YFA0308404)the National Natural Science Foundation of China(Grant Nos.12034003 and 91950201)+1 种基金the Science and Technology Commission of Shanghai Municipality(Grant No.20JC1415900 and 2019SHZDZX01)the Program of Shanghai Academic Research Leader(Grant No.20XD1400300)。
文摘Electroluminescence from a p-type Ga As(110)surface was induced by tunneling electrons in a scanning tunneling microscope under both polarities of bias voltage.The optical spectra exhibit a polarity-independent luminescence peak at 1.47 eV resulting from the exciton recombination.However,the quantum yield of photon emission at negative bias voltage is two orders of magnitude weaker than that at positive bias voltage.Moreover,the luminescence at negative bias voltage shows the linear dependence of bias voltage,distinct from the rapid rise due to resonant electron injection at positive bias.Furthermore,the threshold bias voltage for electroluminescence at negative bias is nearly twice the bandgap of Ga As,not simply satisfying the energy conservation for the creation of an electron–hole pair.Through theoretical calculation,we propose an impact ionization model to nicely explain the newly observed electroluminescence at negative bias voltage.We believe that this mechanism of impact ionization could be readily applied to other nanoscale optoelectronics including 2D semiconductors and 1D nanostructures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61925402,61851402,and 61734003)Science and Technology Commission of Shanghai Municipality,China(Grant No.19JC1416600)+1 种基金National Key Research and Development Program of China(Grant No.2017YFB0405600)Shanghai Education Development Foundation and Shanghai Municipal Education Commission Shuguang Program,China(Grant No.18SG01).
文摘Due to their unique characteristics,two-dimensional(2D)materials have drawn great attention as promising candidates for the next generation of integrated circuits,which generate a calculation unit with a new working mechanism,called a logic transistor.To figure out the application prospects of logic transistors,exploring the temperature dependence of logic characteristics is important.In this work,we explore the temperature effect on the electrical characteristic of a logic transistor,finding that changes in temperature cause transformation in the calculation:logical output converts from‘AND’at 10 K to‘OR’at 250 K.The transformation phenomenon of temperature regulation in logical output is caused by energy band which decreases with increasing temperature.In the experiment,the indirect band gap of MoS2 shows an obvious decrease from 1.581 eV to 1.535 eV as the temperature increases from 10 K to 250 K.The change of threshold voltage with temperature is consistent with the energy band,which confirms the theoretical analysis.Therefore,as a promising material for future integrated circuits,the demonstrated characteristic of 2D transistors suggests possible application for future functional devices.
