Local structure of uncapped and Si capped Ge quantum dots grown on Si(100) has been probed by X ray absorption fine structure spectroscopy. It is found that the uncapped Ge dots are partially oxidized and partially al...Local structure of uncapped and Si capped Ge quantum dots grown on Si(100) has been probed by X ray absorption fine structure spectroscopy. It is found that the uncapped Ge dots are partially oxidized and partially alloyed with Si. The amount of Ge present in the Ge phase is found to be about 20 30%. In the Si capped sample, Ge is found to be dissolved in silicon, the fraction of Ge atoms existing as pure Ge phase being not more than 10%.展开更多
The electric characteristics of Ge quantum dot grown by molecular beam epitaxy in Si matrix were investigated by admittance spectroscopy and deep level transient spectroscopy. The admittance spectroscopy measurements ...The electric characteristics of Ge quantum dot grown by molecular beam epitaxy in Si matrix were investigated by admittance spectroscopy and deep level transient spectroscopy. The admittance spectroscopy measurements show that the activation energy of 0.341eV can be considered as the emitting energy of hole from the ground state of the quantum dot. And the capacitance variation with temperature of the sample shows a platform at various frequencies with reverse bias (0.5 V,) which indicates that the boundary of space charge region is located at the quantum dot layer where the large confined hole concentration blocks the further extension of space charge region. When the temperature increases from 120K to 200K, the holes in the dot emit out completely. The position of the platform shifting with the increase of the applied frequency shows the frequency effects of the charges in the quantum dot. The deep level transient spectroscopy results show that the charge concentration in the Ge quantum dot is a function of the pulse duration and the reverse bias voltage, the activation energy and capture cross-section of hole decrease with the increase of pulse duration due to the Coulomb charging effect. The valence-band offsets of hole in Ge dot obtained by admittance spectroscopy and deep level transient spectroscopy are 0.341 and 0.338eV, respectively.展开更多
我们在前 cimer 激光退火下面的 Ge 和 SiGe 量点的现在的不同松驰机制。自从在 Ge 点和 Ge 层之间没有接口，变粗和在 Ge 的紧张在 Ge 电影上点的点表演的松驰的调查被脱臼放松，当 Si0.77Ge0.23 电影上的 SiGe 点由格子失真放松到协...我们在前 cimer 激光退火下面的 Ge 和 SiGe 量点的现在的不同松驰机制。自从在 Ge 点和 Ge 层之间没有接口，变粗和在 Ge 的紧张在 Ge 电影上点的点表演的松驰的调查被脱臼放松，当 Si0.77Ge0.23 电影上的 SiGe 点由格子失真放松到协调的块时，它源于在 SiGe 块和 Si0.77Ge0.23 电影之间的明显的接口。结果被范德比尔特和 Wickham 建议并且支撑是理论，并且也表明那没有体积散开 oGeurs 在退火的前 cimer 激光期间。展开更多
文摘Local structure of uncapped and Si capped Ge quantum dots grown on Si(100) has been probed by X ray absorption fine structure spectroscopy. It is found that the uncapped Ge dots are partially oxidized and partially alloyed with Si. The amount of Ge present in the Ge phase is found to be about 20 30%. In the Si capped sample, Ge is found to be dissolved in silicon, the fraction of Ge atoms existing as pure Ge phase being not more than 10%.
基金Project(60276025) supported by the National Natural Science Foundation of China
文摘The electric characteristics of Ge quantum dot grown by molecular beam epitaxy in Si matrix were investigated by admittance spectroscopy and deep level transient spectroscopy. The admittance spectroscopy measurements show that the activation energy of 0.341eV can be considered as the emitting energy of hole from the ground state of the quantum dot. And the capacitance variation with temperature of the sample shows a platform at various frequencies with reverse bias (0.5 V,) which indicates that the boundary of space charge region is located at the quantum dot layer where the large confined hole concentration blocks the further extension of space charge region. When the temperature increases from 120K to 200K, the holes in the dot emit out completely. The position of the platform shifting with the increase of the applied frequency shows the frequency effects of the charges in the quantum dot. The deep level transient spectroscopy results show that the charge concentration in the Ge quantum dot is a function of the pulse duration and the reverse bias voltage, the activation energy and capture cross-section of hole decrease with the increase of pulse duration due to the Coulomb charging effect. The valence-band offsets of hole in Ge dot obtained by admittance spectroscopy and deep level transient spectroscopy are 0.341 and 0.338eV, respectively.
