Applications of Silicon-Based Optoelectronics

Silicon-based optoelectronics is a diversified technology that has grown steadily but not exponentially over the past decade. Some applications—such as smart-pixel signal processing and chip-to-chip optical interconnects—have enjoyed impressive growth, whereas other applications have remained quiescent. A few important applications such as optical diagnosis of leaky metal-oxide-semiconductor-field-effect-transistor circuits, have appeared suddenly. Over the years, research and development has unveiled some unique and significant aspects of Si-based optoelectronics. The main limitation of this technology is the lack of practical silicon light sources—Si lasers and efficient Si light-emitting devices (LEDs)—though investigators are “getting close” to the LED. Silicon-based optoelectronics refers to the integration of photonic and electronic components on a Si chip or wafer. The photonics adds value to the electronics, and the electronics offers low-cost mass-production benefits. The electronics includes complementary-metal-oxide semiconductors (CMOS), very large-scale integration (VLSI), bipolar CMOS, SiGe/Si heterojunction bipolar transistors, and heterostructure field-effect transistors. In this discussion, we will use a loose definition of optoelectronics that includes photonic and optoelectronic integrated circuits (PICs and OEICs), Si optical benches, and micro-optoelectromechanical (MOEM) platforms. Optoelectronic chips and platforms are subsystems of computer systems, communication networks, etc. Silicon substrates feature a superior native oxide, in addition to excellent thermal, mechanical, and economic properties. Silicon wafers “shine” as substrates for PICs and OEICs.