Fabrication of Nitride Semiconductor Vertical Microcavity LEDs and Prospects for Blue-Violet Vertical-Cavity Surface-Emitting Lasers

摘要

InGaN vertical microcavity light emitting diodes (LEDs) have been fabricated and characterized. Electrically conductive nitride n-type distributed Bragg reflectors (DBRs) with high reflectivity can be obtained by controlling growth conditions precisely. Furthermore, AlGaN/GaN superlattice-based DBRs in which cracking is suppressed have been successfully grown. Reflectivity of the superlattice DBRs were revealed to be as high as those of conventional DBRs. Effective hole current injection into the microacvity was realized by using indium-tin-oxide (ITO) as a p-type contact material. Microcavity effects were clearly observed in optical characteristics of the microcavity LEDs. At present, we have also achieved to grow nitride DBRs with higher reflectivity up to 99%, with which realization of blue-violet vertical-cavity surface-emitting lasers (VCSELs) can be expected.