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Quick Fabrication VCSELs for Characterisation of Epitaxial Material

Future Compound Semiconductor Manufacturing Hub, School of Physics and Astronomy, Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24 3AA, UK
IQE Plc., Pascal Close, St. Mellons, Cardiff CF3 0LW, UK
Institute for Compound Semiconductors, Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24 3AA, UK
Author to whom correspondence should be addressed.
Academic Editors: Wolfgang Elsaesser, Mark Hopkinson and Im Sik Han
Appl. Sci. 2021, 11(20), 9369;
Received: 4 September 2021 / Revised: 29 September 2021 / Accepted: 7 October 2021 / Published: 9 October 2021
(This article belongs to the Special Issue III-V Semiconductor Nanostructures)
A systematic analysis of the performance of VCSELs, fabricated with a decreasing number of structural elements, is used to assess the complexity of fabrication (and therefore time) required to obtain sufficient information on epitaxial wafer suitability. Initially, sub-mA threshold current VCSEL devices are produced on AlGaAs-based material, designed for 940 nm emission, using processing methods widely employed in industry. From there, stripped-back Quick Fabrication (QF) devices, based on a bridge-mesa design, are fabricated and this negates the need for benzocyclcobutane (BCB) planarisation. Devices are produced with three variations on the QF design, to characterise the impact on laser performance from removing time-consuming process steps, including wet thermal oxidation and mechanical lapping used to reduce substrate thickness. An increase in threshold current of 1.5 mA for oxidised QF devices, relative to the standard VCSELs, and a further increase of 1.9 mA for unoxidised QF devices are observed, which is a result of leakage current. The tuning of the emission wavelength with current increases by ~0.1 nm/mA for a VCSEL with a 16 μm diameter mesa when the substrate is unlapped, which is ascribed to the increased thermal resistance. Generally, relative to the standard VCSELs, the QF methods employed do not significantly impact the threshold lasing wavelength and the differences in mean wavelengths of the device types that are observed are attributed to variation in cavity resonance with spatial position across the wafer, as determined by photovoltage spectroscopy measurements. View Full-Text
Keywords: VCSEL; fabrication; manufacture VCSEL; fabrication; manufacture
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MDPI and ACS Style

Baker, J.; Allford, C.P.; Gillgrass, S.-J.; Forrest, R.; Hayes, D.G.; Nabialek, J.; Hentschel, C.; Davies, J.I.; Shutts, S.; Smowton, P.M. Quick Fabrication VCSELs for Characterisation of Epitaxial Material. Appl. Sci. 2021, 11, 9369.

AMA Style

Baker J, Allford CP, Gillgrass S-J, Forrest R, Hayes DG, Nabialek J, Hentschel C, Davies JI, Shutts S, Smowton PM. Quick Fabrication VCSELs for Characterisation of Epitaxial Material. Applied Sciences. 2021; 11(20):9369.

Chicago/Turabian Style

Baker, Jack, Craig P. Allford, Sara-Jayne Gillgrass, Richard Forrest, David G. Hayes, Josie Nabialek, Curtis Hentschel, J. I. Davies, Samuel Shutts, and Peter M. Smowton. 2021. "Quick Fabrication VCSELs for Characterisation of Epitaxial Material" Applied Sciences 11, no. 20: 9369.

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