A Fundamental Study of Triode Amplifier Devices in the Optical Range

本课题旨在实现我们最近提出的光学频率范围内的三极管放大器件。该器件结合了电子在输入端的光子辅助隧穿和在输出端由于电子波的节拍而发射的电磁波。对纳米结构晶体的生长、制备过程以及器件操作进行了详细的理论分析，为器件的实现奠定了基础。在器件运行的理论分析中，首次进行了全量子力学处理，指出输出端的电磁波辐射来源于光子辅助隧穿电子的集体超辐射。通过这种分析，可以讨论电子散射、频率极限、信噪比等因素的影响。结果表明，虽然电子散射…对于器件的制作，首先研究了CaF2/CdF2/Si异质结的晶体生长，因为CaF2/CdF2/Si异质结具有较大的势垒，因此在这种材料体系中，能量量子化将是非常显著的。我们提出了纳米区外延，将晶体生长限制在100 nm量级的小区域内。利用该技术获得了特性非常均匀的共振隧穿结构，并首次对其结构依赖性进行了系统的实验研究。采用氢端衬底和倾斜衬底研究了这种材料体系在Si(100)衬底上的晶体生长，并首次在室温下在Si(100)衬底上获得了负微分电阻。提出了在异质界面使用二维电子气，在输入和输出端口使用缝隙线的器件结构，为器件的理论基础、晶体生长和器件结构奠定了基础。较少

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 … More 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