SUPPRESSION OF QUANTUM-WELL INTERMIXING IN GAAS ALGAAS LASER STRUCTURES USING PHOSPHORUS-DOPED SIO2 ENCAPSULANT LAYER/

A phosphorus-doped silica (SiO2:P) cap containing 5 wt% P has been dem onstrated to inhibit the bandgap shifts of p-i-n and n-i-p GaAs/AlGaAs quantum well laser structures after rapid thermal processing. The int ermixing suppression has been attributed to the fact that SiO2:P is mo re dense and void free compared with standard SiO2 together with a str ain relaxation effect of the cap layer during annealing. Band gap shif t differences as large as 100 meV have been observed from samples capp ed with SiO2 and With SiO2:P. The n-i-p structure showed a higher degr ee of intermixing compared to p-i-n structure. This behaviour has been attributed to the rise of Fermi level in the n doped structure, throu gh which the formation energy of Ga vacancies is reduced compared to t he p doped structure. (C) 1997 American Institute of Physics.