EXPERIMENTAL-EVIDENCE OF EXCITON WAVE-FUNCTION SHRINKAGE IN INXGA1-XAS INP MULTI-QUANTUM-WELLS/

We have studied the confinement effect on the ground state of the n = 1 heavy exiton in InxGa1-xAs/InP Multi Quantum Wells (MQW) grown by Ch emical Beam Epitaxy (CBE). Absorption optical spectra obtained in the excitonic region on several MQW were analyzed as a function of the wel l thickness L(z), ranging in the interval 25-80 angstrom, and as a fun ction of the temperature (8-300 K). In agreement with the theory, a cl ear enhancement of the oscillator strength calculated by the integrate d area of the heavy exiton absorption peak with the well thickness dec rease, has been observed; such increase is a direct evidence of the ex citon wavefunction shrinkage and is one of the firstly reported in Inx Ga1-xAs/InP MQW. The ratio between 1s light and heavy exciton absorpti on area was used to evaluate their related reduced mass ratio mu(lh)/m u(hh) = 1.36 +/- 0.075 in excellent agreement with the calculated one (1.35).