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

1. 谐振隧道二极管的极限速度及其结构参数设计控制谐振隧道二极管的极限速度是由两个势垒之间多重反射过程的时间延迟决定的。通过皮秒激光光谱直接测量了该延迟，发现当AlAS势垒厚度从40a减小到28a时，延迟从600ps呈指数级减小到60ps。观察到的趋势与理论预测非常一致，即延迟由不确定关系h/ E给出，其中E是电子隧穿透射谱中共振峰的宽度TT^x(E)。因此，发现有必要采用极薄的屏障以实现高速运行。此外，系统地阐明了/Al Ga As势垒中Al含量对二极管特性的影响，表明在室温下，使用纯AlAs势垒可以最有效地获得高峰谷比。一种新的谐振隧道二极管高速光开关方案研究了将谐振隧道二极管与量子条纹调制器串联在一起的方法，当在混合器件上施加固定的偏置电压时，可以提供一种新型的光双稳器件。当入射光较弱（1mW）时，器件是不透明的，但当光强超过一定值时，器件变成透明的。对该移动装置进行了分析，表明可以在低功率（30fJ）下实现非常高速（100ps）的开关，并且具有优异的通断比（<相似或等于>10:1）。成功的操作是演示

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