MOVPE growth and characterization of GaAs/GaAsBi/GaAs p-i-n structure

In this work, we report on the epitaxial growth and characterization of the GaAs/GaAsBi/GaAs p-i-n structure. The samples were grown on a GaAs (001) substrate using atmospheric pressure metal-organic vapor phase epitaxy (AP-MOVPE). The effect of the barrier growth temperature of p and n GaAs layers and GaAsBi thickness on the behavior of the structure was investigated. The conductivity of GaAs layers is optimized by adjusting mutually the growth temperature and the III/V ratio. High resolution X-ray diffraction (HRXRD) and spectroscopic photoreflectance (PR) techniques have been used to quantify the physical properties of compound materials. For a structure having a nanometric dimension, we have not obviously identified any signature of confined level in the diluted GaAsBi layer, which is supposed to be a well. To avoid any overlap between barrier and well PR responses, the Bi content has been increased using an alternating injection growth procedure for the epitaxy of the GaAsBi active region. A relatively high Bi composition of 7% has been successfully reached, and a quantum confinement is observed at 1.15 eV. This finding is supported by the numerical results giving the confined levels determined from the resolution of the Schro<spacing diaeresis>dinger equation in the GaAsBi well. This work illustrates that the GaAs/GaAsBi/GaAs structures can be achieved with a very high Bi content by the adoption of alternated bismuth flows during growth and provides a promising route towards the realization of high-efficiency infrared emitters.