Resonant-cavity organic light-emitting diodes for low-cost optical interconnects between CMOS silicon circuits

The possibility to integrate an optical emitter at any point in a silicon integrated circuit would represent a major breakthrough in the field of optical interconnects between circuits or in the same circuit. The outstanding properties of luminescent organic semiconductors, such as their ability to be deposited on various substrates and their efficiency, make them good candidates for this kind of applications. In addition, microcavities limit the spectral and spatial distributions of the emitted light, which makes the integration of the light source easier in an optical interconnection system. We studied resonant-cavity organic light-emitting diodes (RC-OLEDs) such as Al/ITO/CuPc/TPD/Alq3/Al which were made on silicon substrates. ITO was deposited by magnetron sputtering and the other materials by vacuum evaporation through masks. Aluminum was chosen to make the mirrors because it is widely used in CMOS technology. The thickness of each layer was chosen so that the optical length of the cavity is 3 * lambda (res) / 2 where lambda (res) is the resonant wavelength. We described these planar multilayer microcavities using a transfer-matrix multiplication method. The devices were characterized by photoluminescence and electroluminescence, and the experimental results are in good agreement with the model. The current-voltage characteristics were measured while the electrical model is currently under study.