OPTIMIZATION OF GROWTH-PARAMETERS OF SHORT-PERIOD INGAAS/INP SUPERLATTICES FOR WANNIER-STARK MODULATORS

In this work we describe the influence of the growth parameters on the optical and crystallographic properties of InGaAs/InP short period superlattices (SPSLs) The optimized growth conditions applied for multiquantum wells are no longer appropriate when the period thickness is below 85 Angstrom and quasi-continuous growth interruption times are required. The assessment of new growth conditions enabled the realization of SPSL structures with ultimate period of 31 Angstrom presenting good optical and structural properties. The electron wave-function coherence length of seven SPSLs was evaluated. Application of these devices enabled the realization of Wannier-Stark modulators operating at 1545 nm with extinction ratio of 22 dB at 2.5 V reverse bias. The electron wave-function was evaluated, for the first time in the InGaAs/InP system, to be at last seven SPSL periods using both transmittance and photocurrent methods. The on state attenuation determined using Wood's method is below 2 dB in the range between 1540 and 1555 nm. SPSL structures are therefore well suited for the realization of guided wave electro-optic modulators based on the Wannier-Stark effect.