Layer disordering of GaAs-AlGaAs superlattices by diffusion of laser-incorporated Si

Recently, a laser-scanning technique for patterning layerdisorderinghasbeen reported in which silicon impurities are incorporated bylaserirradiation into GaAs-AlGaAs heterostructures. The sample is subsequently annealed to diffuse the Si deep into the heterostructure. The GaAs-AlGaAs layers are locally intermixed by diffusion of the silicon impurities. In this report, this two-step process of laser-assisted disordering is studied in detail with several material characterization techniques. Scanning electron microscopy and secondary ion mass spectrometry are used to correlate the extent of the layer-disordered region with the presence of laser-incorporated Si and oxygen. Transmission electron microscopy (TEM) is used to obtain high resolution images of thedisordered/as-grown interface and to evaluate the crystallinity of the laser-affected material. TEM images allowthedetermination of the distribution of the Al and Ga constituents atthe interface between the impurity-disordered alloy and the as-grown crystal. The data indicate a more rapid Si diffusion in the GaAs layers relative to the Al-rich layers. The data are discussed in the context of device fabrication.