Optoelectronic integrated circuits: Silicon and nitride LEDs integrated onto a single chip for one-bit digital counters

Silicon-based semiconductor devices dominate the microelectronics industry and are used for the fabrication of high density integrated circuits comprising of memory and processing devices. However, silicon has an indirect band gap, which severely limits its use for fabricating photonic devices such as light emitting diodes (LEDs) and lasers.

One-bit counter consisting of a p-MOSFET and GaPN light emitting diode

An innovative solution to this problem would be the integration of silicon devices with LEDs produced using direct band gap compound semiconductors, in the form of optoelectronic integrated circuits (OEICs).

Here, Akihiro Wakahara and colleagues at Toyohashi University of Technology (Toyohashi Tech) demonstrate the first realization of a one-bit counter circuit OEIC with an optical output consisting of silicon field effect transistors integrated with gallium phosphide nitride (GaPN) LEDs on a single chip.

The monolithic integrated circuits were fabricated using lattice matched Si/GaPN/Si heterostructures grown on silicon substrates in a dual chamber molecular beam epitaxy (MBE) system. Notably, growth of the silicon capping layer at a high temperature of 850℃ led to a dramatic reduction of the threshold voltage to -2.1 V and an increase of the channel mobility of the p-MOSFET to 82 cm2Vs. This improvement is attributed to a decrease in phosphorus incorporation during the growth of the capping layer.

The one-bit counter circuit fabricated using the n-Si/p-GaPN/n-GaPN/GaP/n-Si heterostructure exhibited normal operation, where red light emission from the input and output indicators was in synchronization with the input and output logical voltages.

Reference

• K.Yamane[1], K. Noguchi[1], S. Tanaka[1], Y. Furukawa[1], H. Okada[2], H. Yonezu[1], and A. Wakahara[1],[2]
Operation of Monolithically-Integrated Digital Circuits with Light Emitting Diodes Fabricated in Lattice-Matched Si/III–V–N/Si Heterostructure
Applied Physics Express 3, 074201, (2010)
Abstract and restricted links: http://apex.jsap.jp/link?APEX/3/074201/
DOI: 10.1143/APEX.3.074201

• [1] Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
• [2] Intelligent Sensing System Research Center, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan

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Transmission electron microscope image showing the n-Si/p-GaPN/n-GaPN/GaP/Si heterostructure

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(a) Circuit diagram of the one-bit counter; (b) Optical image of an actual circuit; (c) Synchronization of the LED emission with input and output circuit voltages

Published: 24 Mar 2011

Contact details:

Toyohashi University of Technology
1-1 Hibarigaoka, Tempaku
Toyohashi, Aichi
441-8580, JAPAN

+81-532-44-6577
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http://www.tut.ac.jp/english/newsletter/research_highlights/research03.html Article in Toyohashi Tech e-Newsletter http://www.gcoe.tut.ac.jp/english/gaiyou/index4.html Frontiers of Intelligent Sensing http://apex.jsap.jp/link?APEX/3/074201/ Abstract and restricted links for paper 'Operation of Monolithically-Integrated Digital Circuits with Light Emitting Diodes Fabricated in Lattice-Matched Si/III–V–N/Si Heterostructure'

Reference: 

• K.Yamane[1], K. Noguchi[1], S. Tanaka[1], Y. Furukawa[1], H. Okada[2], H. Yonezu[1], and A. Wakahara[1],[2] Operation of Monolithically-Integrated Digital Circuits with Light Emitting Diodes Fabricated in Lattice-Matched Si/III–V–N/Si Heterostructure Applied Physics Express 3, 074201, (2010) Abstract and restricted links: http://apex.jsap.jp/link?APEX/3/074201/ DOI: 10.1143/APEX.3.074201