SKM 2021 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 19: Poster Session IV

HL 19.16: Poster

Donnerstag, 30. September 2021, 13:30–16:30, P

Reduction of crystal defects in GaP buffer layers grown on Si(100) by MOCVD — •Manali Nandy¹, Agnieszka Paszuk¹, Markus Feifel², Christian Koppka¹, Peter Kleinschmidt¹, Frank Dimroth², and Thomas Hannappel¹ — ¹TU Ilmenau, Gustav-Kirchhoff-Straße 5, 98693, Ilmenau — ²Fraunhofer Institute for Solar Energy Systems ISE, Freiburg 79110, Germany

The performance of III-V-on-Si multijunction solar cells is still limited by a high density of defects at the GaP/Si heterointerface and in the III-V buffer layers. Here, in order to improve the crystal quality of the GaP(100) buffer layer, we modified the GaP pulse nucleation by substituting the first five TEGa pulses with TMAl. The influence of Al on the defect density in the GaP buffer layers is investigated by electron channeling contrast imaging. 60 nm thick GaP(100) buffer layers grown on GaP nucleation exhibit short misfit dislocations (MDs) and therefore, a high density of threading dislocations (TDs). In contrast, GaP(100) buffer layers grown on GaP/AlP nucleation exhibit less, but longer MDs, which result in a lower density of TDs. In addition, the density of stacking faults and stacking faults pyramids in the GaP layer grown on the AlGaP nucleation is significantly reduced. The surface morphology at the initial growth stage of GaP buffer layers grown on AlGaP nucleation, is smoother compared to buffer layer grown on the GaP nucleation. The application of Al in the GaP nucleation process provides a two-dimensional, smooth layer on which subsequent, high-quality GaP films could be grown, and therefore, shows a promising pathway for improving the performance of III-V-on-Si devices.