Fabrication And Characterization Of Si-Based Self-Rolled-Up Ⅲ-Ⅴ Microtubes

In recent years, self-rolled-up microtubes have attracted much attention. They have shown broad application prospects in physical electronics, optics, biology, and micro-electromechanical systems due to their excellent optical and electrical properties. In particular, Si-based self-rolled-up microtubes can introduce the high performance optical microcavity onto Si substrates, which will build a good platform for Si-based photonics and is also very meaningful for the realization of Si-based optoelectronic interconnects. In general, semiconductor microtubes on Si are fabricated by two methods. One is the self-rolling of GeSi/Si bilayers on Si substrate. The other is the transfer method in which Ⅲ-Ⅴ microtubes formed on GaAs are transferred to Si substrates. However, both of these two methods have their limitations. Therefore, direct growth of Ⅲ-Ⅴ semiconductors on Si and corresponding fabrication of Ⅲ-Ⅴ microtubes on Si show distinct advantages.My study is focused on the fabrication and the characterization of Si-based InGaAs/GaAs self-rolled-up microtubes. The main work and results are shown as follows. 1) Through cooperation, we grow the InGaAs/GaAs bilayers on the Si substrates by three-step GaAs/Si metamorphic growth. A50nm-thick AlAs layer is used as the scarifical layer and the strained bilayer is consisted of Ino.2Gao.gAs(15nm)/GaAs(35nm). Each layer can be clearly distinguished from XRD pattern.2) We succeeded in fabricating the InGaAs/GaAs self-rolled-up microtubes of the rectangular model rolling type directly on Si substrate. All the microtubes are rolled-up from the same direction neatly and evenly. Also, large scale Si-based microtube arrays are fabricated.3) We succeeded in fabricating the InGaAs/GaAs microtubes of tearing rolling type on GaAs substrate. The controllable fabrication of the microtubes is achieved. Then this method is transfer to the fabrication of Si-based torn microtubes and achieves the preliminary success.4) The structural properties of the Si-based self-rolled-up microtubes of rectangular model rolling type are studied and comparison with the GaAs-based microtubes of the same structure has been made. We found that the diameter of the Si-based microtubes (～4.2μm) is a little lager than that of the GaAs-based microtubes (～3.5μm). And the tube-wall of the Si-based microtubes shows more fluctuation than the GaAs-based microtubes.5) The optical properties of the Si-based self-rolled-up microtubes of rectangular model rolling type are studied. Through measurement, we found that the PL peak position of the Si-based microtubes shows a little redshift (～3nm) relative to that of the as grown structure. And the emission from the ends of the microtubes show stronger intensity compared to the center part of the tubes (～3times).