2 May 1997 AlxGayIn1-x-yAs/AlGaAs quantum well lasers at 670 to 750 nm
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AlxGayIn1-x-yAs/AlGaAs quantum well lasers offer the prospect of devices at intermediate wavelengths between about 690 nm and 750 nm with applications in areas such as photodynamic therapy. The larger thermal conductivity of AlGaAs compared to that of AlGaInP could make the AlxGayIn1-x-yAs system attractive for high power devices. The incorporation of indium in the quantum well also improves material quality and introduces compressive strain which enhances the intrinsic performance beyond that of the phosphide system due to the larger spin orbit splitting and more similar electron and hole density of states in AlxGayIn1-x-yAs compared with GaxIn1-xP. We have modeled the gain and radiative recombination of AlxGayIn1-x-yAs wells with Al0.45Ga0.55As barriers at a wavelength in the region 720 to 730 nm. This shows that the intrinsic gain-current characteristic is superior to that of an idealized GaInP/AlGaInP laser at the same wavelength. Devices have been fabricated, which operate at 685 nm and 750 nm at room temperature, and the length dependence of the threshold current, measured as a function of temperature between 140 K and 400 K, analyzed. At the shorter wavelength the room temperature threshold current is dominated by thermally activated carrier loss from the well. Although this could be reduced by further optimization, short wavelength operation is severely restricted by the band gap of the AlGaAs barriers and this material system will be of greatest benefit for devices at wavelengths greater than about 710 nm.
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Peter M. Smowton, Peter Blood, Paul C. Mogensen, John Stuart Roberts, "AlxGayIn1-x-yAs/AlGaAs quantum well lasers at 670 to 750 nm", Proc. SPIE 3001, In-Plane Semiconductor Lasers: from Ultraviolet to Midinfrared, (2 May 1997); doi: 10.1117/12.273783; https://doi.org/10.1117/12.273783


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