|Budget Amount *help
¥15,700,000 (Direct Cost: ¥15,700,000)
Fiscal Year 2002: ¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 2001: ¥8,500,000 (Direct Cost: ¥8,500,000)
This project aimed at realization of a triode amplifier device in the optical frequency range which we proposed recently. The device operates with the combination of the photon-assisted tunneling of electrons at the input and their emission of electromagnetic wave at the output port due to the beat of electron waves. The nanostructure crystal growth, fabrication process, and detailed theoretical analysis of the device operation were performed as a fundamental research toward the realization of the device. The results are summarized as follows.
For the theoretical analysis of the device operation, a full quantum mechanical treatment was done for the first time, noting that the emission of electromagnetic wave at the output is originated from the collective superradiance from the photon-assisted tunneling electrons. By this analysis, it became possible to discuss the influence of electron scattering, frequency limit, siginal-to-noise ratio. It was shown that, although the electron scatter
ing reduces the gain, its influence is not significant if the photon energy is smaller than the electron energy broadening due to the scattering, and a possibility of amplification up to far or mid infrared region was estimated.
For the fabrication of the device, crystal growth of CaF2/CdF2/Si heterostructure was investigated as the first step, because energy quantization is expected to be remarkable in this material system due to large potential barriers. We proposed the nano-area epitaxy, in which the crystal growth is restricted into 100nm-order small region. By this technique, the resonant tunneling structure with very uniform characteristics was obtained, and systematic experiments for the structure dependence were performed for the first time. Crystal growth on Si(100) substrate was also studied using hydrogen-terminated substrates and inclined substrates in which the atomic steps on the surface is controlled, and the negative differential resistance was obtained at room temperature for the first time on Si(100) substrate for this material system. The device structure using two-dimensional electron gas at the heterointerface and slot lines at the input and output ports was proposed for relatively easy fabrication.
By these results, theoretical bases, crystal growth, and device structures were established. Less