We have observed Be diffusion in an AlGaAs/GaAs quantum-well (QW) laser structure grown at ∼700 °C from the p-AlGaAs cladding layer into the adjacent graded index (GRIN) AlGaAs and GaAs regions and beyond. This displaces the p/n junction from the AlGaAs/GaAs heterojunction. The Si dopant in n-AlGaAs GRIN and cladding layers influences the diffusion of Be. When the GRIN regions on p and n sides are doped with Be and Si, respectively, the displacement of the p/n junction is significantly reduced. Oxygen, a common contaminant in AlGaAs irrespective of the growth technique, tends to accumulate at the inverted GaAs/AlGaAs heterointerface in the GRIN region. Furthermore, the Be-doped Al0.6Ga0.4As cladding layer has an increased amount of O compared to its Si-doped counterpart. In addition, cathodoluminescence (CL) intensity from the GaAs QW was more than an order of magnitude higher in structures with undoped GRIN regions compared to doped ones. The decreased CL and the increased amount of O in Be-doped layers suggest that oxygen related nonradiative centers are incorporated in the QW active region of lasers with an intentionally Be-doped p-side GRIN region. Note that Be coincorporates O from the ambient, but diffused Be does not carry O along. Therefore, we recommend that the Be doping in p-side GRIN region should be avoided and the n-side GRIN region should be doped with Si to minimize O contamination, Be diffusion, and p/n junction displacement. Although the results are presented for AlGaAs/GaAs QW lasers, similar arguments can be applied for the growth of strained InGaAs/AlGaAs QW lasers.
No takes yet. Share an insight, caveat, or question.
Chand et al. (1992) studied this question.