Basic study of coherent hot electron generation and its application for ultrafast devices

本研究主要研究相干超热电子的产生和测量，研究了利用波动原理控制超热电子输运的可能性和纳米间距电子波光栅的实现，电子波器件的实现取决于电子的相干性，准相干长度为100 nm已经估计调制掺杂结构中的平衡电子在非常低的温度和非常低的施加电压下相当长。另一方面，非平衡电子或热电子的相位被L0声子的自发辐射打破，其相位制动时间被认为短至0.2ps。然而，对于工作在4K以上的温度和适当的电压条件下的电子波器件，如何利用热电子是一个值得考虑的问题。 ...更多信息 隧穿二极管（RTD）。当电子的相位在RTD的阱中被打破时，谐振能级的宽度增加。然后通过测量RTD的共振能级宽度，我们可以估计阱中热电子的相位制动时间或相干特性。因此，我们用OMVPE制作了GaInAs/InP双势垒RTD，并从I-V曲线的二阶导数测量了RTD的谐振能级宽度。我们比较了能级宽度对势垒厚度的依赖性与理论估计的相干长度。当电子能量为100 meV时，GaInAs在4K时的表观相干长度为80- 120 nm。我们计划利用量子光栅中的电子波衍射来控制超热电子的输运，发展超细节距光栅的纳米加工技术。我们采用电子束光刻、特殊的湿法化学腐蚀和有机金属气相外延生长相结合的方法，在GaInAs中制备了40 nm间距的InP光栅。此外，为了观察电子波的超细衍射图样，我们用剥离技术制备了间距为40 nm的超细电极阵列。为了实现嵌入式光栅与超细电极的对准，我们采用了电子束对准技术。少

In this research, the generation and the measurement of the coherent hot electron, the possibility of transport control of the hot electron based on the wave principle and the realization of the nanometer-pitch electron-wave grating were studied.The realization possibility of the electron wave device depend on the coherence of the electron. The coherent length of the quasi-equilibrium electron in the modulation doped structure has been estimated to be quite long at very low temperature and under very low applied voltage. On the other hand, the phase of the non-equilibrium electron or the hot electron is broken by the spontaneous emission of the L0-phonon and its phase braking time is supposed to be as short as 0.2ps. However, for operation at temperature higher than 4K and under appropriate voltage application, it is interesting to consider how to use the hot electron for the electron wave device.We are estimating the coherent properties of the hot electron using the double barrier res … More onant tunneling diode(RTD). When the phase of the electron is broken in the well of the RTD,the width of the resonant level increases. Then by measuring the width of the resonant level of the RTD,we can estimate the phase braking time or the coherent properties of the hot electron in the well. Therefore we have fabricated GaInAs/InP double barrier RTDs by OMVPE.From the second derivatives of the I-V curves, we have measured widths of resonant levels of RTDs. We compared the dependence of the level width on the barrier thickness with theory to estimate the coherent length. The apparent coherent length in GaInAs was 80-120nm at 4K when the energy of the electron was 100meV.Projecting to control the transport of the hot electron by electron wave diffraction in a quantum grating, we are developing nanofabrication technology of ultrafine pitch grating. We have achieved 40nm-pitch InP gratings embedded in GaInAs by combining electron-beam lithography, special wet chemical etching and organometallic vapor phase epitaxy overgrowth. Furthermore, to observe the ultrafine diffraction pattern of the electron wave, we have fabricated 40nm-pitch arrays of ultrafine electrodes by the lift-off technique. To align the embedded grating and the ultrafine electrode, we have developed the electron-beam alignment technique by using Platinum marks. Less