InGaAs/GaAsSb superlattice structure is very attractive in photodetectors and light emitting devices. However, the growth of high quality GaAsSb alloys is a challenge. Recently, a research team from the Chinese Academy of Sciences (CAS) has successfully obtained high quality InGaAs/GaAsSb superlattice structures based on a broad analysis of growth mechanisms .
The high crystalline quality of GaAsSb and InGaAs is desired for applications in opto-electronics. Professor Jianxin Chen and his group from CAS set out to tackle this program. After years of research, they have comprehensively studied growth mechanisms and have successfully obtained high quality InGaAs/GaAsSb superlattice structures. Their work, entitled “Growth mechanism and optical properties of InGaAs/GaAsSb superlattice structures”, was published in SCIENCE CHINA, 2015, Vol. (4).
The high quality of GaAsSb alloys is crucial to the fabrication of high quality InGaAs/GaAsSb superlattice material. In order to control the quality, the researchers have studied the effects of different factors on the growth GaAsSb alloys. They explained the incorporation behavior of Sb and As in GaAsSb using the non-equilibrium thermodynamic model. As shown in Fig. 1, the calculated results (solid line) are in good agreement with the experimental data (solid circles). The non-equilibrium thermodynamic model can well describe the MBE growth process and the incorporation rule of As and Sb in the GaAsSb material.
Fig. 1: Antimony composition as a function of Sb and As beam equivalent pressure ratio FSb2 / FSb2 + FAs2.
By optimizing the growth parameter, a high quality InGaAs/GaAsSb superlattice was obtained. A slight blue-shift of photoluminescence (PL) peak energy in the InGaAs/GaAsSb superlattice PL spectrum was observed, which is attributed to the band bending effect of photo-excited carriers. The group also analyzed the temperature dependence of PL peak energy and integrated intensity.
 Jin C, Xu Q Q, Chen J X. Growth Mechanism and Optical Properties of InGaAs/GaAsSb Superlattice Structures. SCIENCE CHINA Physics, Mechanics & Astronomy, 2015, 58(4): 044202.