AN OPTICAL STUDY OF INTERDIFFUSION IN STRAINED INP-BASED HETEROSTRUCTURES

The interdiffusion behavior of Inl(1-x)Ga(x)As(1-y)P(y)/In1-x'Gax'As1- y'Py' multiple quantum well heterostructures with varied built-in stra in and layer thicknesses, has been investigated by monitoring their ph otoluminescence (PL) properties. All samples annealed at 850 degrees C , have consistently exhibited a blueshift of the heavy hole exciton li ne as a result of atoms interdiffusion across the heterointerfaces. A quantitative analysis of their PL spectra permitted to deduce the foll owing important characteristics of the interdiffusion process: (i) Fro m the data on a nearly strain-compensated structure with constant P/As ratio and In-rich wells, studied here for the first time, we show tha t the blueshift of the excitonic line is consequent of group III atoms interdiffusion alone, like in GaAs/GaAlAs system, and the In-Ga inter diffusion can be described with a diffusion coefficient D-In-Ga approx imate to 4.72 X 10(-16) cm(2) /s; (ii) In the case of lattice matched and compressively-strained structures, a simultaneous interdiffusion o n group III and V sublattices has been assumed to yield an effective i nterdiffusion coefficient ranging from 3.83 to 5.51 x 10(-16) cm(2)/s.