Reduced Threshold Current in Bipolar Diode Lasers by Non-square Quantum Well Growth
Allsopp, D W E
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By device simulation, it is shown that non-square quantum well growth (well shaping) provides a means for reducing the threshold current of bipolar quantum well diode lasers. Calculations of subband structure, optical matrix elements and laser gain are performed based on a 4-band (electron, heavy-hole, light-hole, split-off-hole) Hamiltonian with Burt-Foreman Hermitianization. A non-optimized, compressively strained, InGaAs-AlGaAs (on GaAs) shaped well laser, operating at 0.97 µm is predicted to show improvements in both radiative and non-radiative current performance compared to a device based on an optimal square quantum well of the same well width and emission wavelength. These improvements result from modification of subband structure giving greater subband separation in the shaped well than in the square well.