Gillgrass, S. J., Baker, J., Allford, C. P., Davies, J. I., Shutts, S. and Smowton, P. M. 2025. AlGaAs VCSELs grown on thin 150 mm germanium substrates. JPhys: Photonics 7(3), article number: 35033. (10.1088/2515-7647/adef1f)
To reduce material usage and minimise device cost the use of reduced substrate thickness is considered in high volume vertical-cavity surface-emitting laser (VCSEL) manufacturing. For large-diameter VCSEL wafers, germanium (Ge) is emerging as an alternative substrate solution. In this work, VCSEL structures designed for 940 nm emission are grown by metal–organic vapour-phase epitaxy on 150 mm (6 inch) germanium substrates of thickness 675, 450 and 225 µm. Using on-wafer testing of fabricated devices, threshold current density, differential resistance, and emission wavelength are compared across the three substrate thicknesses, with results demonstrated for the first time on a Ge wafer thickness of 225 µm. These results underline the potential of thin Ge substrates for reduced material usage in VCSEL manufacturing.
Yan, Z. et al. 2025. MOCVD-grown InAs/InP quantum dot lasers with low threshold current. Optics Express 33(15), pp. 31195-31203. (10.1364/OE.568365)
In this work, we have demonstrated low-threshold-current and high-yield InAs/InP QD lasers grown by MOCVD. Deep-etched ridge waveguide lasers were fabricated with a narrow 4 µm ridge width and top–top metal contact configuration. The devices achieved threshold currents of 17 mA for 300 µm cavity length and 28 mA for 1000 µm cavity length. Lasing operation was maintained up to 120 °C. These results confirm the potential of MOCVD-grown InAs/InP QD lasers as light sources for the C- and L-band applications and for future integration on silicon platforms.
