Planar monolithic integration of a photoconductive switch and a nipi-modulator into a smart pixel for opto-optical switching

Abstract

In this paper we report the first successful regrowth and processing of a normal- incidence nipi- modulator monolithically integrated with a special photoconductive switch into a smart pixel. Previously we have demonstrated that our special photoconductive switch provides high output currents suitable to drive directly either an electrooptical modulator or a surface emitting vertical cavity laser in hybrid versions of novel smart pixels with excellent performance data [1]. Surface-normal electro-optical modulators based on n-i-p-i- structures are very attractive components for smart pixels because they allow high-speed operation, require low driving voltage, exhibit high switching contrast and have a wide spectral bandwidth [2]. The MBE growth of the n-i-p-i- modulators requires the Epitaxial Shadow Mask technique (ESM-MBE). In order to integrate monolithically n-i-p-i modulators grown by ESM-MBE with our photoconductive switches into smart pixels we have developed a new InGaP/GaAs mask technology in which the p-i-n structure for the fabrication of the switch is part of the shadow mask layer structure, as depicted in Fig. 1. The key feature for this technology is the extremely high bi-directional etch selectivity of InGaP/GaAs.