Development of High-speed Resonant Tunneling Diodes for Room Temperature Application

1.共振隧穿二极管的极限速度及其结构参数控制共振隧穿二极管的极限速度受两个势垒之间多次反射过程的时延控制。用皮秒激光光谱直接测量了这一延迟，发现当AlAs势垒厚度从40A减小到28A时，延迟从600ps显著减小到60ps。观察到的趋势与理论预测非常一致，即延迟是由不确定比h/E给出的，其中E是电子隧穿透射谱Tt^x(E)中的共振峰的宽度。因此，为了高速运行，必须采用极薄的障碍物。此外，系统地阐述了二极管特性对Al/Al-Ga As势垒中Al含量的影响，表明在室温下使用纯AlAs势垒是获得高峰谷比的最有效方法。一种用于共振隧道二极管高速光开关的新方案当在混合器件上施加固定的偏置电压时，通过串联谐振隧道二极管和量子板调制器的集成，可以提供一种新型的光学双稳器件。当入射光很弱(1 MW)时，该装置是不透明的，但当光强超过一定值时，该装置就会变得透明。对移动器件的分析表明，在低功率(30fJ)的情况下，可以实现超高速(100ps)的开关，并且具有良好的开关比(&lt；类似或相当于&gt；10：1)。成功的手术就是示范

1. Speed limit of Resonant Tunneling Diodes and its control by Structural Parameter Design The ultimate speed of resonant tunneling diodes is governed by the time delay associated with multiple reflection process between the tow barriers. This delay was directly measured by picosecond laser spectroscopy and found to be reduced expoentially from 600 ps to 60 ps as the thickness of AlAS barriers is reduced from 40 A to 28 A. The observed tendency is shown to agree very well with the theoretical prediction that the delay is given by the uncertainty releatio h/ E where E is the width of the resonant peak in the tunneling transmission spectrum TT^x(E) of electrons. Hence, it is found necessary to abopt extremely thin barriers for high speed operation. In addition, the variation of diode characteristics on Al content of/Al Ga As barriers is systemtically elucidated, indicating that the use of pure AlAs barriers is most efficient in achieving high peak-to-valley ratio ratio at room temperatures.2. A Novel Scheme for High Speed Optical Switching of Resonant Tunneling Diodes An integration of a resonant tunneling diode with a quantum Strak modulators by connecting them serially is found to provide a novel optical bistable device, when a fixed bias voltage is applied across the hybrid device. The device is opaque when the incident light is weak( 1mW), but becomes transparent, as the light intensity exceed a certain value. The movel device is analysed to show that very high speed ( 100ps) switching is possible with low power ( 30fJ) with excellent on-off latio (<similar or equal>10:1). A successful operation is demonstrssion