THE RELATION BETWEEN GA VACANCY CONCENTRATIONS AND DIFFUSION LENGTHS IN INTERMIXED GAAS AL0.35GA0.65AS MULTIPLE-QUANTUM WELLS/

Photoluminescence (PL) measurements were performed in order to investi gate the intermixing behavior of GaAs/Al0.35Ga0.65As multiple quantum wells due to thermal treatment. The PL spectra for the annealed sample s show the step like signals, and show that the magnitude of the inter mixing of Al and Ga induced by thermal annealing in GaAs/Al0.35Ga0.65A s MQWs is different according to the depths. The results of the PL spe ctra obtained using a procedure of successive layer-by-layer chemical etching show that the atomic mixing is maximum near the sample surface and decreases monotonically with the depth. This result is caused by the different distribution of the diffused Ga vacancy. The potential p rofile of the GaAs/Al0.35Ga0.65As as a function of the diffusion lengt h was investigated, and electron and hole energy subbands in the MQWs were calculated by a variational method making use of the calculated p otential profile. The Ga vacancy concentration corresponding to the de pth of the MQWs was investigated from the Al interdiffusion length and the distribution of the diffused Ga vacancy, and this result indicate s that the diffusion length of Al is proportional to the logarithmic f unction of the Ca vacancy concentration.