Suppression of dopant redistribution in AlGaAs/GaAs laser-HEMT structures for optoelectronic transmitters grown by molecular beam epitaxy

Detailed studies of segregation and diffusion of the dopants Si and Be in MBE grown AlGaAs/GaAs heterostructures for optoelectronic devices are presented. Segregation of Si could be suppressed by lowering the substrate temperature during the growth of a few monolayers after the deposition of the doped layers. Solubility limits of Be were observed to depend on the Al mole fraction. Be diffusion in the laser structures was negligible at doping concentrations below these solubility limits. As an application, transmitter OEICs were fabricated using laser-HEMT structures grown with optimized growth conditions. The devices operated successfully at 15 GBit/s.