Heterogeneous integration of CdS filters with GaN LEDs for fluorescence detection microsystems

Microassembly of a hybrid fluorescence detection microsystem by heterogenous integration of a CdS thin film filter, an (In, Ga)N thin film blue LED, and disposable PDMS microfluidic device onto a Si PIN photodetector substrate is described. The CdS thin film filter was deposited directly onto a photodetector by pulsed-laser deposition. A thin film (In, Ga)N LED was then transferred by a novel "pixel-to-point" laser lift-off process from the sapphire growth substrate to the silicon photodetector substrate. The final integration step was achieved by positioning a disposable polymer microfluidic device onto the excitation/detection subsystem. pixel-to-point transfer is potentially an enabling microassembly process for the fabrication of multicolor fluorescence-based bioassays and chemical detection microsystems. (C) 2003 Elsevier B.V. All rights reserved.