Influence of mask design on the growth of InGaAs/InAlAs quantum wells on patterned substrates

The influence of mask geometry on growth enhancement and alloy composition was investigated for InGaAs/InAlAs multiple quantum well structures grown o n patterned InP (100) substrates by low pressure metalorganic vapor phase e pitaxy. The masks used have a window 20 mu m wide and width varying between 5 and 75 mu m. Two different regimes have been observed. For masks with wi dth smaller than 40 mu m both growth enhancement and alloy composition infl uence the lowest optical transition energy, while for masks wider than 50 m u m, alloy composition remains stable and selectivity is essentially due to growth enhancement. With the results obtained together with calculations o f the Schrodinger equation within the effective mass approximation, one con cludes that, with proper mask design, it is possible to obtain an array of several modulators with slightly different operation wavelengths which are all polarization independent. In addition, the waveguiding characteristics of a modulator sample selectively grown was analysed by near field experime nts. Comparing the results with a sample conventionally grows, one conclude s that the selective growth technique essentially does not influence the wa veguiding properties. (C) 2000 Published by Elsevier Science S.A. All right s reserved.