Feasibility Study of Traveling Wave Devices Using Compound Semiconductor Superlattice Structures

本研究旨在探讨利用化合物半导体超晶格结构制作新型行波元件的可行性。主要结果如下：[1]对有限维半导体等离子体超晶格结构中的行波相互作用进行了理论分析。研究了理想的非色散慢波结构和叉指慢波结构，后者涉及到有限维半导体等离子体中空间谐波场分量的复杂的自洽计算机场分析。分析表明了微波和毫米波行波器件的可行性。论证了等离子体德拜屏蔽长度对有源层厚度的重要性，指出了超晶格结构的优越性。[2]具有高击穿场强和对半导体有源层的最小沉积损伤的介质间隔层对于慢波和半导体载波之间的耦合至关重要。为此，我们成功地开发了一种使用50 Hz等离子体的PCVD氮化硅室温沉积工艺。[3]制作了分别以n-GaAs MOVPE单层、AlGaAs-GaAs MBE异质结构层和n-InP单层作为有源层的三种叉指型行波器件。两端导纳测量清楚地表明行波相互作用在微波频率在所有类型的实验装置的存在。此外，InP器件的两端导纳的测量行为显示出与详细的计算机模拟的结果非常一致，建立了具有最大相互作用增益的器件的设计理念。

The purpose of the research is to investigate the feasibility of new-type of traveling wave devices using compound semiconductor superlattice structures. The main results are the following:[1] Theoretical analysis of the traveling wave interactions was made on the superlattice structures with finite dimensions of semiconductor plasma. An ideal non-dispersive slow wave structure and an interdigital slow wave structure were studied with the latter involving a complicated self-consistent computer field analysis over space harmonic field components present in the semiconductor plasma of finite dimensions. The analysis has clearly shown the feasibility of microwave and millimeter-wave traveling wave devices. Importance of Debye screening length of plasma with respect to the active layer thickness was demonstrated and the advantage of superlattice structure was indicated.[2] Dielectric spacers with a high breakdown field strength and minimal deposition damage to Semiconductor active layers is essential for coupling between slow-wave and semiconductor carrier wave. For this purpose, a room temperature deposition process of PCVD silicon nitride was successfully developed, using 50Hz plasma.[3] Three kinds of interdigital traveling wave devices having n-GaAs MOVPE single layer, AlGaAs-GaAs MBE hetero structure layers and n-InP single layer as the active layer, respectively, were fabricated. Two-terminal admittance measurements clearly indicated presence of traveling wave interactions at microwave frequencies in all types of the experimental devices. Furthermore, the measured behavior of two-terminal admittance of the InP device showed an excellent agreement with the result of the detailed computer simulation, establishing the design philosophy for devices with the maximum interaction gain.