Polarization - Doped InGaN LEDs and Laser Diodes for Broad Temperature Range Operation

This work reports on the possibility of sustaining a stable operation of polarization-doped InGaN light emitters over a particularly broad temperature range. We obtained efficient emission from InGaN light-emitting diodes between 20 K and 295 K and from laser diodes between 77 K and 295 K under continuous wave operation. The main part of the p-type layers was fabricated from composition-graded AlGaN. To optimize injection efficiency and improve contact resistance, we introduced thin Mg-doped layers of GaN (subcontact) and AlGaN (electron blocking layer in the case of laser diodes). In the case of LEDs, the optical emission efficiency at low temperatures seems to be limited by electron overshooting through the quantum wells. For laser diodes, a limiting factor is the freeze-out of the magnesium-doped electron blocking layer for temperatures below 160 K. The GaN:Mg subcontact layer works satisfyingly even at the lowest operating temperature (20 K).The names of the individual files correspond to the numbering of the figures in the paper Muhammed Aktas ,Szymon Grzanka, Łucja Marona, Jakub Goss, Grzegorz Staszczak, Anna Kafar and Piotr Perlin; Polarization-Doped InGaN LEDs and Laser Diodes for Broad Temperature Range Operation - https://doi.org/10.3390/ma17184502Files included in this collection:Figure 1. Structure of LED (a) and laser (b) with polarization-doped p-cladding layer.Figure 2. Energy - band diagram (@ 3.5 V) and refractive index of the laser structure (a) zoomed at an active area (b) and EBL area (c). The regions corresponding to (b,c) are marked by green dashed rectangles in the picture (a). Vertical axes are identical for all graphs.Figure 3. Polarization doped LED’s I–V measurement (a); EL measurement at 100 mA (b).Figure 4. Polarization-doped laser structure’s L-I-V measurement in pulse mode (a). Threshold currents and slope efficiencies in pulse mode (b).Figure 5. Temperature dependence pulse mode EL spectra of polarization-doped laser structure at low current (a), high currents (b), and their peak wavelength (c).Figure 6. L-I-V measurement in CW mode of the polarization-doped laser structure (a). Threshold currents and slope efficiencies in CW mode (b), with pulse mode results for reference.Figure 7. Temperature dependence EL spectra of polarization-doped laser structure at 1 mA (a), above the threshold current (b), and their peak wavelength (c) in CW mode.Figure 8. Thermal resistance of polarization doping laser structure.