2018年7月24日星期二

Annealing Effects on Ge/SiO2 Interface Structure in Wafer-Bonded Germanium-on-Insulator Substrates

We have investigated annealing effects on Ge/SiO2 interfaces in wafer-bonded germanium-on-insulator substrates using transmission electron microscopy and electron energy loss spectroscopy. A number of nanometer-sized hollows were observed at the Ge/SiO2 interfaces after annealing at 500 and 600 °C, while the density of these hollows was very small after annealing at 700 and 800 °C. The hollows are attributed to the formation of amorphous oxides of Si-rich Si1-xGexO2. The mechanism for the formation and disappearance of these amorphous hollows on the Ge substrates is discussed.


Source:IOPscience

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2018年7月1日星期日

Diode-Pumped Passively Q-Switched and Mode-Locked Nd:LuVO4 Laser with a GaAs Wafer

Simultaneous Q-switching and mode locking (QML) in a diode-pumped Nd:LuVO4 laser using a GaAs wafer as saturable absorber is experimentally demonstrated in a Z-type folded cavity. The repetition rate of the Q-switched pulse envelop increases from 48 to 116 kHz and the average output power increases from 88 to 498 mW as the pump power increases from 1.7 to 8.2 W. It is found that QML is easily realized in a Z-type cavity. The mode-locked pulse inside the Q-switched pulse has a repetition rate of 111 MHz, and its average pulse width is estimated to be about 345 ps. Using a hyperbolic secant square function and considering the Gaussian distribution of the intra-cavity photon density to model the mode-locked pulse, we propose a developed rate equation model for the Q-switched and mode-locked lasers. The numerical solutions of the equations are in good agreement with the experimental results.


Source:IOPscience

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