Novel nanolasers, nano-LEDs, and modal cutoff confinement light emitters

Semiconductor metal nanocavity lasers and light emitting diodes together with novel modal cutoff confinement light emitters are investigated for optical interconnection application in future dense photonic integrated circuits. Several different cavity structures are designed, processed, and characterized, and demonstrate operation with current injection at room temperature. We first examined metal-cavity quantum-dot surface-emitting micro-lasers. Different sizes of metal-DBR cavities are fabricated with cavity volume reduction both in the lateral and vertical dimensions following our theoretical design rules to optimize the performance. One of the smallest electrical injection lasers is demonstrated with a minimum diameter of 1-m and a minimum hybrid DBR-Ag mirror of only 5.5 pairs. From the analysis of various sizes of diameter devices, it is found that self-heating is significant in the smaller diameter devices due to both the higher series resistance and higher threshold gain leading to a high carrier density. For the further cavity volume reduction, we have designed, fabricated, and characterized metal-encapsulated nano-light-emitters with bulk semiconductor in the active region. The first principal design rule is used to estimate the fundamental mode resonance and threshold condition. The result based on this design rule agrees very well with the numerical three-dimensional calculation. The device recipes have been developed through multiple iterations from the device characterization. The smallest metal cavity diode emitter with electrical injection is 0.086 03 in terms of emitting wavelength at room temperature. It is shown that the series resistance of metal-encapsulated nanocavities is much smaller than the metal coated VCSEL, suppressing the heat generation for the small diameter devices. The fabrication improvement shows a narrow linewidth cavity mode in the metal nanocavity with a volume of 1.23 03 at room temperature. To solve the problem of the high radiation loss caused by a metal mirror, we proposed novel nano/micro-cavities edge-emitting laser using the mode-cutoff reflection of the fundamental TE mode from a metal-semiconductor-metal (MSM) region. The devices are examined by multiple aspects for their function, both qualitatively from the principle of operation and quantitatively from the analytical study of reflection coefficient and numerical simulations by the 2D and 3D models for practically designed devices. The numerical simulations including the metal loss suggest that room temperature lasing with a reasonable threshold material gain is achievable. We have also developed processing recipes to fabricate the device without any semiconductor dry-etching process. The preliminary electrical and optical characterizations of the proposed devices are performed showing excellent I-V characteristics with a thin hetero-junction diode. The light output curve shows a super-linear behavior suggesting possible lasing in the cavity volume less than 3