Speaker
Description
Nanowire (NW) arrays are promising candidates for next generation optoelectronic devices. They offer the unique possibility to form heterojunctions using materials with a large lattice mismatch, enabled by strain relaxation along the radial direction of the nanowire. In photovoltaics, this allows for tandem junction solar cells using material combinations which are not compatible in traditional planar form. In this work (as published in [1]), nanowire arrays containing a top segment of GaxIn1-xP are investigated, as part of our work towards InP/GaInP NW tandem solar cells.
The commonly used Ga precursor for GaInP nanowires grown by use of Metal-Organic Vapor Phase Epitaxy (MOVPE) is trimethylgallium (TMGa). However, TMGa has the disadvantage of incomplete pyrolysis at typical NW growth temperatures (400 – 480 °C), which leads to high precursor losses and complicates the growth dynamics. Therefore, we investigate the use of the alternative precursor triethylgallium (TEGa) by making a direct comparison between NWs grown using TEGA and TMGa at otherwise identical conditions. Growth rates, resulting NW materials composition, and time-resolved photoluminescence (TRPL) lifetimes are investigated for nominally intrinsic as well as uniformly doped NW arrays.
For doped NWs, the p-type dopant Zn strongly affects the Ga content of InGaP grown using TMGa. This has been studied in [2], and was explained by an enhanced pyrolysis of TMGa in the presence of DMZn. The strong influence of DMZn on the growth dynamics is absent in the sample grown with the TEGa precursor, which is a direct consequence of the different pyrolysis pathway of TEGa. Our results favor the use of the TEGa precursor for growth of GaInP NW optoelectronic devices, where a constant GaInP composition is desirable.
- D. Alcer et al., Phys. Status Solidi B 2000400 (2021)
- G. Otnes et al., Nano Letters, 17, 2, 702–07 (2017)
| Speaker Country | Sweden |
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