Basic Research of GaInAs Ultrafast Transistor Using Diffraction of Ballistic Electron

这是使用新工作原理的超快晶体管的基础研究。我们从实验上研究了半导体中的弹道输运，特别是热电子的波特性。同时，我们发展了半导体中人工建立的势栅引起的电子波绕射理论。主要研究结果如下：1.利用金属有机气相外延技术(OMVPE)制备了非常陡峭的GaInAs/InP异质结。利用这些异质结，我们已经实现了热电子注入到GaInAs中。2.制作了测量热电子输运性质的装置。作为测量的结果，我们估计了GaInAs中超热电子的平均自由程长度大于200 nm。此外，我们还观察到了77K时器件伏安特性的反常振荡，理论上可以用势垒对电子波的多次反射来解释。这一观测表明，超热电子的相干长度可能大于500 nm。3.利用电子束曝光法和一种新型的湿法化学刻蚀技术，在InP的表面形成了非常精细的栅格。该光栅的间距最小为70 nm。该技术可用于形成用于电子波衍射的光栅。4.分析了光栅场对电子波的衍射特性。结果表明，利用GaInAs/InP光栅，理论上可以在0.1V的开关电压下实现电子流的开关，即使在77K也可以利用这一现象，从而为利用半导体中热电子的波特性实现新型器件提供了重要的知识。

This is a basic research for an ultrafast transistor using a new principle of operation. We have investigated experimentally the ballistic transport, in particular, the wave property of the hot electron in the semiconductor. In parallel, we have developed a theory of the electron wave diffraction due to the potential grating artificially built in the semiconductor. The summary of the result is as follows.1.We have achieved to create very abrupt GaInAs/InP heterojunctions by organometallic vapor phase epitaxy(OMVPE). By using these heterojunctions, we have achieved to inject the hot electron into GaInAs. 2.We have fabricated devices to measure properties of hot electron transport. As the result of the measurement, we have estimated the mean free path length of the hot electron in GaInAs as more than 200nm. Furtehrmore, we have observed anomalous oscillations in V-I characteristics of devices at 77 K, which have been explained theoretically by a multiple reflection of the electron wave due to potential barriers. This observation suggests that the coherence length of the hot electron may be more than 500nm. 3.By using the electron beam ilthography and a novel wet chemical etching, we have achieved to form very fine gratings on surfaces of InP. The pitch of the grating was as small as 70 nm. This technique can be applied to form the grating for the electron wave diffraction. 4.We have analyzed the diffraction characteristics of the electron wave due to the grating. As the result, by using GaInAs/InP grating, we can theoretically switch the electron flow by the switching voltage of 0.1 V. We can use this phenomenon even at 77 K.From the above, we have acquired important knowledge for realization of the new device using wave property of the hot electron in the semiconductor.