Edge-emission electroluminescence study of as-grown vertical-cavity surface-emitting laser structures

We report polarized edge- and front-emission electroluminescence studies on red-emitting vertical-cavity surface-emitting laser (VCSEL) structures. Th e measurements were performed nondestructively on pieces of as-grown wafers using indium-tin-oxide-coated glass electrodes. The front-emission spectra helped determine the Fabry-Perot cavity-mode wavelength, while the edge-em ission spectra were used to identify the wavelength of ground-state emissio n from the quantum wells (QWs) in the active region. However, measurements on edge-emitting laser (EEL) structures with a similar QW active region rev eal that the peaks of the edge-emission spectra are always slightly redshif ted with respect to front emission. We show that this arises due to reabsor ption effects and then appropriately correct for it in the VCSELs by studyi ng such shifts in the equivalent EELs. Thereafter, by comparing the experim ental results with theoretical calculations and simulations, we estimate th e composition, strain, and material quality of the QWs in the VCSEL active regions. Finally, we comment on the usefulness of comparing the two orthogo nally polarized edge-emission spectra. (C) 2000 American Institute of Physi cs. [S0021-8979(00)01715-1].