Raman and X-ray characterization of III-V interfaces

In_xGa_1-xAs/InP devices are frequently applied for high-speed electronics and opto-electronics in the near infrared. A crucial property is the quality of the InGaAs/InP interfaces. During growth, which is usually performed by metalorganic vapour phase epitaxy, these interfaces may be deteriorated by different intermixing effects, which result from the switching of the group III as well as the group V elements at each interface. We report on the application of Raman spectroscopy and X-ray diffractometry on nominally lattice-matched InGaAs/InP multi quantum wells (MQWs) for interface analysis. Raman spectroscopy allows the identification of possible ternary and quaternary interface layers from their characteristic lattice vibration frequencies. X-ray diffractometry yields the average strain and periodicity of the MQW. Furthermore, it allows the identification of interface layers from the intensity of the satellite peaks in the diffraction pattern. In this paper we show how the Raman and X-ray results may be used as a guideline for optimizing the growth parameters. For the resulting MQWs the high quality of crystalline structure and interfaces gives rise to confined phonons in the Raman spectrum and “pendellosung” fringes in the X-ray diffraction pattern