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(a) 2 × 2 μm2 AFM scan of the AlInN-based bottom DBR surface. (b) Schematic drawing of the VCSEL structure. (c) SEM cross-section view of the VCSEL microcavity using FIB for milling.
(a) I-V characteristics of devices using either a RIE p-GaN treatment (blue curve) or a SiO2 layer (red curve) for confining the current. Both devices have a mesa diameter of 80 μm and a current aperture of 8 μm. (b) Picture of a RIE-based device under low CW electrical injection. (c) Near field real space imaging in linear scale of a RIE-based device under pulsed electrical injection with a current aperture diameter of 8 μm.
Output light peak power (violet dots) and cavity mode FWHM (blue dots) as a function of the pulsed driving current. The VCSEL mesa diameter is 60 μm and its current aperture is 8 μm. The lasing threshold current is about 70 mA.
EL spectra measured from the top (a) and bottom (b) sides for pulsed currents below, near, and above lasing threshold. The VCSEL mesa diameter is 60 μm and its current aperture is 8 μm. Bragg modes are visible outside the bottom AlInN-based DBR stopband (b). Inset: near field real space imaging of a lasing VCSEL under a driving current of 100 mA, with a current aperture of 8 μm.
Threshold current densities (Jth) calculated using Eq. (3) as a function of the top dielectric DBR reflectivity. The red and blue curves correspond to the VCSEL structure presented in this paper and another one using a λ/8 ITO current spreading layer placed at a node of the electrical field, respectively.
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