Study of Scattering Process in Tunnel-Device by Phonon Pulse.

在目前的研究中，最重要和必不可少的技术是具有极高的时空分辨率和灵敏度的热脉冲(声子脉冲)技术。为此，在约5×10~(-6)Torr的氧气气氛中制备了颗粒状结构的铝薄膜，用于加热器(声子发生器)和测辐射热计(接收器)。为了提高空间分辨率，采用了光刻技术，即加热器和测辐射热计的尺寸约为48×48亩^2。为了避免很窄(几纳秒)的电磁感应(穿透)。脉冲电流、加热器和测辐射热计垂直设置，使用微同轴电缆。用数值去卷积技术消除了有限热容和电容量引起的信号延迟。研究表明，在用分子束外延方法制备的隧道器件中，在硅衬底和SiGe薄膜之间的边界处的晶体形变即使在小于100A的很薄的区域内也会引起很大的声子散射和声子模转换。也就是说，这种方法对于研究小区域的晶体形变是非常敏感和有用的。此外，为了扩展这一研究，用氢等离子体溅射方法在Si衬底上进行了碳化硅薄膜的外延生长。我们还明确指出，在硅片上以令人惊讶的低温(800ﾟC)外延生长了3C-碳化硅薄膜，然后我们将继续使用3C-碳化硅薄膜进行这一研究。

In the present research, the most important and indispensable technology which must be accomplished is the heat-pulse(phonon-pulse) technology with ultimate high resolution in space and time, and sensitivity. For this purpose, aluminium thin'films with granular structure deposited in oxygen gas atmosphere of about 5 X10^<-6> Torr were prepared, and these were used for both heater(phonon generator)and bolometer(receiver). For high space resolution, a photolithography technique was employed, namely the size of heater and bolometer was about 48*48 mu^2. To avoid the electromagnetic induction(break-through) caused by a very narrow(a few nano-sec.) pulse current, the heater and the bolometer were set vertically to each other, and micro coaxial-cable was used. The signal delay caused by finite heat and electric capacities were removed by numerical decoinbolution technique.In the present investigation, it was made clear that a crystal deform at boundaries between Si base and SiGe films in a tunneling-device preparedi by MBE method gives rise to a large phonon scattering and a phonon mode conversion even by very thin regions less than 100 A.namely, this method is very sensitive and useful to investigate the crystal deform of small region.Furthermore, to expand this investigation, an epitaxial growth of SiC film on-to Si base was carried out by means of hydrogen plasma sputtering method, and it was also made clear that 3C-SiC film was epitaxially grown onto Si wafer at a surprising low temperature, 800ﾟC, and then we would like to continue this in-vestigation using 3C-SiC films.