Metamorphic Resonant Tunneling Diodes and Its Application to Chaos Generator ICs

摘要

In this paper we discuss the properties of InGaAs/AlAs metamorphic resonant tunneling diodes (RTDs) on GaAs substrates. The current-voltage, surface roughness, and low-frequency noise characteristics were investigated to clarify the effect of step-grading buffer layers. No degradation of the current-voltage characteristics were observed despite the large surface roughness due to a lattice mismatch. Moreover, low-frequency noise measurements showed only 1/f noise without special peak structures, and the amplitudes of which were comparable to those of the lattice-matched ones. Next, we fabricated resonant tunneling frequency divider ICs, which is based on the bifurcation phenomenon in a chaos system, on metamorphic substrates. A maximum operation frequency of 88 GHz and good phase noise properties were obtained, which are similar to those of the lattice-matched ones. These results demonstrate the effectiveness of the step-grading buffer layers even for the RTDs that consist of very thin layers and are sensitive to crystal qualities.