The effect of Te as a surfactant on OMVPE of InAs quantum dots

The state of the art in space solar cells utilizes epitaxially grown III-V multijunction cells with champion devices exceeding 30% efficiency under 1-sun. An array of self-organized InAs quantum dots (QD) within a GaAs matrix is one approach to enable significant efficiency improvements by extending the spectral bandwidth of the GaAs cell. In this paper, the surfactant effect of Te on the properties of strain compensated InAs quantum dots grown on GaAs has been investigated. Large Te surface doses prior to QD epitaxy lead to a degradation in QD structural and optical quality. Low Te doses also affect the optical quality of QD. The effect of a thin delta-doped layer (Si, Zn, and Te) in close proximity to the QD layers within a 5-period QD strain-compensated solar cell was also investigated. The Te-doped QD cell exhibits weaker sub-gap absorption. The results suggest that large surface Te concentrations affect the nucleation behavior of InAs QDs. The 1-sun IV and spectral response results suggest that the presence of Te-doped layers degrade the cell performance of QD solar cells.