Be–Zn interdiffusion and its influence on InGaAsP lasers fabricated by hybrid growth of chemical beam epitaxy and metalorganic vapor phase epitaxy

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Abstract
We have studied the dopant redistribution between a chemical beam epitaxy (CBE) grown InGaAsP laser structure and a metalorganic vapor phase epitaxy overgrown InP layer. Secondary ion mass spectroscopy analysis reveals that Zn and Be atoms deeply interdiffuse in the adjacent InP layers for a Zn doping of 10 18 cm −3 and that a fraction of Zn atoms go through the CBE InP and penetrate the laser structure guide layer. We have found that the Zn outdiffusion is significantly suppressed by reducing the Be doping concentration from 10 18 to 5×10 17 cm −3 . As a result, for tensile-strained InGaAsP multiquantum well (MQW) buried-heterostructure (BH) lasers, the threshold current and internal loss decrease from 13 to 9 mA and 15 to 10 cm −1 by lowering the Be doping, respectively. InAsP MQW BH lasers have an internal loss of 5.5 cm −1 .