Semiconductor laser or array formed by layer intermixing

Abstract

A fabrication process and several structures for an index-guided laser diode formed by IILD or for a multiple wavelength laser array containing stacked semi-conductive active layers with quantum wells. The laser wavelength is varied laterally by effectively inactivating quantum wells which have transition wavelengths longer than that desired in the selected portion of the device. The quantum wells are inactivated by intermixing them with the surrounding high band gap semiconductor layers. To accomplish this intermixing without affecting the active layer in nearby regions, a finite source of impurity inducing or promoting intermixing is located in proximity to the quantum well to be intermixed, and the sample is annealed under conditions which allow for lateral patterning of the impurity-induced intermixing. Alternatively, the body is capped over the quantum well to be inactivated with a material which induces vacancies in semi-conductive material during thermal annealing, thus promoting vacancy-enhanced intermixing of the undesired quantum well. The intermixing can also be brought about by patterned annealing or selective laser heating which produces local annealing, or by use of two different caps. For the index-guided laser diode, the flanking index-guiding regions are formed by IILD from a buried impurity source, in which surface conditions are controlled to promote impurity diffusion to the flanking regions but not to the active stripe region between the flanking regions.