Electronic devices and their highly integrated components formed from semiconductor crystals contain complex three-dimensional (3D) arrangements of elements and wiring. Photonic crystals, being analogous to semiconductor crystals, are expected to require a 3D structure to form successful optoelectronic devices. Here, we report a novel fabrication technology for a semiconductor 3D photonic crystal by uniting integrated circuit processing technology with micromanipulation. Four- to twenty-layered (five periods) crystals, including one with a controlled defect, for infrared wavelengths of 3-4.5 microm, were integrated at predetermined positions on a chip (structural error <50 nm). Numerical calculations revealed that a transmission peak observed at the upper frequency edge of the bandgap originated from the excitation of a resonant guided mode in the defective layers. Despite their importance, detailed discussions on the defective modes of 3D photonic crystals for such short wavelengths have not been reported before. This technology offers great potential for the production of optical wavelength photonic crystal devices.

In this paper, we discuss unique light localizations in photonic crystal line defect waveguides based on two different concepts. The first concept is an additional defect doping that breaks the symmetry of the line defect. Even though such a defect is open to the line defect, the optical field is well confined around the defect at cutoff frequencies of the line defect. This expands the design flexibility of microcavities and allows effective mode controls such as the single-mode operation. The lasing action of such cavities in a GaInAsP photonic crystal slab was experimentally observed by photopumping at room temperature. The second concept is a chirping of the waveguide structure. The photonic band of a waveguide mode has a band edge, at which the group velocity becomes zero. The band-edge condition shifts in a chirped line defect waveguide, so guided light reaches a zero group velocity point and is localized. A macroscopic behavior of this phenomenon was experimentally observed in a waveguide fabricated into a silicon-on-insulator substrate. In addition, a microscopic behavior was theoretically investigated, which suggested its applicability to a group delay device.

This paper experimentally demonstrates the strong enhancement of light extraction efficiency in two-dimensionally arranged microcolumns. They were designed like a honeycomb photonic crystal and fabricated into GaInAsP-InP wafers by using the inductively coupled plasma etching. For the laterally directed light passing through the microcolumns, peculiar transmission characteristics were observed, which could be explained by the Bragg reflection theory, namely, the photonic bandgap (PBG). The measurement of spontaneous lifetime showed that the internal efficiency in the microcolumns was reduced by the surface recombination at sidewalls. In contrast, the light extraction efficiency evaluated from the measured photoluminescence intensity, and the internal efficiency was more than ten times that for a planar wafer. This was thought to be due to the expanded escape cone of internal light by the low effective refractive index, and also due to the strong diffraction and scattering of laterally directed light, which corresponds to the second-order Bragg condition. Such effects are expected not only in photonic crystals but also in some disordered structures. We expect this structure to allow a high-efficiency light-emitting diode (LED), since electronic elements needed for current injection devices can be added independently of the effects.

The spontaneous emission decay in a photonic crystal slab nanocavity with a GaInAsP quantum well active region was measured at room temperature. Even far below lasing threshold, the decay was much faster than that for the as-grown wafer. A consideration including the enhanced spontaneous emission rate by the Purcell effect, intraband relaxation of carriers, nonradiative surface recombination, spatial hole burning, and carrier diffusion enabled us to explain different decay lifetime between on-and off-resonant conditions and between different size cavities. As a result, Ͼ16-fold shorter spontaneous emission lifetime was estimated, which strongly suggests the existence of a large Purcell effect.

We evaluated the surface recombination velocity vs of 1.55 μm GaInAsP microcolumns through the measurement of carrier lifetime using the phase-resolved spectroscopy. We investigated various surface treatments and confirmed that vs was reduced to nearly half of that for as-etched microcolumns by CH4 electron cyclotron resonance plasma irradiation. This result was ensured by the two- to fivefold increase in photoluminescence intensity. The secondary ion mass spectroscopy analysis suggested that the reduction in vs was attributable to the deposition of a polymer, the hydrogenated hard carbon, etc., and/or a carbon deep level formed near the surface.