Erbium-doped silicon light-emitting devices

Research in erbium-doped silicon (Si:Er) is discussed in light of our effort to improve the luminescence performance of our LEDs and to demonstrate an integration scheme for a microphotonic clock distribution system. Excitation from Si:Er can occur int ow ways: (1) direct excitation of an Er ion by high energy electrons or (2) energy transfer from an injected electron-hole pair to an Er ion in the lattice. In an LED the first excitation mechanism corresponds to operation in reverse bias, and the latter corresponds to operation in forward bias. We have studied the forward bias case, and we use an energy pathway model to describe the excitation and de-excitation processes. The competing, nonradiative processes against excitation and spontaneous emission are discussed. Maximization of light output can be approached in three ways: (1) decreasing the number of nonradiative energy pathways, (2) enhancing the probability of the radiative pathway, or (3) simply increasing the concentration of active Er sties. We report specific methods that address these issues, and we discuss more device structures that can be used as emitters, optical waveguides, and optical switches in a fully integrated microphotonic system.