Optical properties of GaInAs/InP multi-quantum wells grown by low-pressure MOVPE

Abstract

The authors have systematically investigated the absorption and derivative absorption of a series of GaInAs/InP multi-quantum well structures (MQWS) grown by low-pressure (LP) metal-organic vapour-phase epitaxy (MOVPE). Excitonic transitions between n>or=1 confined states (electron-heavy holes and electron-light holes) have been resolved, and are seen clearly even at room temperature. Comparison with photoluminescence (PL) data shows Stokes shifts as weak as 4 meV, indicating minor potential fluctuations. These results confirm LP-MOVPE as an attractive approach for growing sophisticated structures over large substrates for optoelectronic device production. Each intrinsic excitonic transition energy was carefully determined by performing theoretical fits in the light of the two-dimensional theory of direct allowed excitonic transitions. Comparing with recent theoretical results, they find a satisfactory agreement but, in some cases, finite departures of the alloy compositions or quantum well widths with respect of the nominal values have been found. This results in sizable shifts of the series of excitonic transitions with respect to the expected positions, which establishes excitonic absorption as a quantitative and non-destructive tool for checking the wells' homogeneity, composition and thickness.