GAAs High-Speed Devices: Physics, Technology, and Circuit Applications

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THE DEVELOPMENT OF GALLIUM ARSENIDE DEVICES AND INTEGRATED CIRCUITS

1.1 GALLIUM ARSENIDE DEVICE DEVELOPMENT

In modern computer and telecommunication applications the most important semiconductors for high-speed devices are silicon and gallium arsenide and its related III–V compounds and solid solutions. Recent advancements in fabrication technology have produced the superlattice semiconductor, which is an artificial one-dimensional periodic structure made up of different semiconductor materials with a period of about 100 Å. Superlattice semiconductors include silicon-based materials (e.g., GeSi/Si) and gallium arsenide-based materials (e.g., AlGaAs/GaAs or InGaAs/GaAs) [Sze90].

Silicon's high density and high speed make it a popular material for very large-scale integrated (VLSI) circuit devices. But the III–V compounds have certain speed advantages over silicon in their higher carrier mobilities and effective carrier velocities. The semi-insulating substrates of the III–V compounds provide lower interconnection capacitances. Research on hybrid material systems based on a heteroepitaxial process has shown that an advanced architecture can be developed whereby high-speed GaAs/AlGaAs devices are located on heteroepitaxially grown islands on a silicon wafer (GaAs on Si), integrated with the silicon VLSI circuits by a suitable metallization process. There are promising developments as well in optical communications for silicon wafers, for example, in electronically triggered compound-semiconductor ...