Effect of rapid thermal annealing on the atomic intermixing of Zn- and C-doped InGaAs/AlGaAs quantum well laser structures

We have studied the effect of annealing on the atomic intermixing of Zn- and C-doped InGaAs/AlGaAs laser structures. Electrochemical capacitance voltage measurements revealed that the carrier concentration in the Zn-doped GaAs contact layers decreased after annealing at 900°C for 60 s. indicating that some of the Zn acceptors were passivated or outdiffused from the surface, whereas in the C-doped samples there was an increase of the camer concentration after annealing. This latter was confirmed by X-ray rocking curve results where there was an increase in the amount of lattice contraction associated with the presence of the substitutional carbon C_As after annealing. Secondary ion mass spectroscopy revealed that the Zn diffused significantly from the top layers to the rest of the structures after annealing at 925 °C, but the SIMS profile did not change significantly for C-doped samples with annealing. This indicates that Zn has a much higher mobility in comparison to carbon. Photoluminescence measurements after etching the samples to various depths showed similar luminescence defects in both Zn- and C-doped samples. The possible mechanism of atomic intermixing for bom Zn- and C-doped samples are discussed.