Basic Research of GaInAs Ultrafast Transistor Using Diffraction of Ballistic Electron

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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.