Silicon Photonics: Fundamentals and Devices

6.1 Introduction

The main obstacle in the widespread use of silicon and related materials lies in the poor light emission properties of these indirect-gap materials. Active research on the optoelectronic properties of silicon and its alloy SiGe was undertaken soon after the announcement of transistors. At first, the motivation behind the work was to know the basic properties. However, with the emergence of silicon as the sole material for microelectronics, work on the realization of an efficient light emitter was intensified. The goal is to develop truly monolithic optoelectronic integrated circuits exhibiting the magic performance of silicon-based microelectronics. The main applications of silicon-based light-emitting devices, that is, light-emitting diodes (LEDs), lasers, and optical amplifiers, are in electronic and optical systems and displays. Optical devices in the wavelength range from 0.4 to 1.6 µm are needed for full-color displays and for sources and amplifiers for standard telecommunications wavelength bands around 1.3 and 1.55 µm. Specific applications for such sources are as transmitters for optical fiber communication, optical interconnects within and between computer chips and boards, optical controllers for phased-array microwave antennas, information display screens, printing elements for xerography, and writing and readout in optical compact disc systems.

Unfortunately, however, the progress in achieving the coveted goal is far from a satisfactory level, in spite ...