Chapter 11 - Semiconductor Monolithic Circuit

Abstract

This chapter describes basic technologies supporting semiconductor monolithic circuits and introduces some examples of the semiconductor monolithic devices. A semiconductor material for active optical devices should have bandgap energy that corresponds to the operation wavelength of light. Quaternary compounds of InGaAsP with arbitrary bandgap energies can be fabricated on InP substrates with a perfect lattice match to the substrates. Controllability of the bandgap is also important in passive devices for obtaining materials with arbitrary refractive index. Waveguides in passive devices require materials with different refractive indexes for the core and cladding regions. Passive devices use semiconductor materials with bandgap wavelength longer than the operating wavelength to avoid band-to-band absorption. Buried heterostructure (BH) waveguides are fabricated in a sequential process that involves etching of the waveguide and regrowth of the cladding material. Most semiconductor active devices such as lasers and amplifiers use a BH structure for waveguiding, mainly for the reliability advantage. It is found that the advantages of arrayed waveguide grating are small device size and potential for integration with other semiconductor devices, such as photodiodes, semiconductor optical amplifiers, and laser diodes.