Silicon-based Digital Counter, Nitride LED Integrated on Single Chip

Another group of researchers have demonstrated an LED chip on a silicon substrate. (See aricle about Bridgelux advance on silicon)

Researchers at Toyohashi University of Technology have demonstrated a one bit opto electronic integrated circuit-based counter circuit with an optical output.
The optical output comes from the integration of silicon field effect transistors (FETs) and gallium phosphide nitride (GaPN) LEDs on a single chip.

At the univesity, Akihiro Wakahara led a team of researchers fabricated the
monolithic integrated circuits with lattice matched Si/GaPN/Si heterostructures grown on silicon substrates in a dual chamber molecular beam epitaxy (MBE) system. Details of the research were published in Applied Physics Express.

During the growth of the silicon capping layer at a high temperature of 850 degrees C the phosphorous incorporation was reduced and the channel mobility of the p-MOSFET increased to 82 cm2Vs.

The one-bit counter circuit had a n-Si/p-GaPN/n-GaPN/GaP/n-Si heterostructure. The device operated normally with the red light emission from the input and output indicator LEDs synchronized with the input and output logical voltages.

While the demonstration was a great success, it likely has little direct applicability to the LED lighting industry because the LED involved is red.

* K.Yamane, et al. Operation of Monolithically-Integrated Digital Circuits with Light Emitting Diodes Fabricated in Lattice-Matched Si/III