Method of making a single heterostructure laser chip having sawn cavities and secondary saw cuts

A method of making a sawn cavity laser chip, which method includes the steps of preparing a single heterostructure device structure single crystal semiconductor wafer by the epitaxial growth of a layer of GaAlAs of one conductivity type upon a GaAs substrate of the opposite conductivity type, cleaving the wafer to obtain a bar of semiconductor material sawing the bar into individual chips, and making secondary saw cuts parallel with the sawn edges to define a laser chip with an inverted Tee cross-section, wherein the secondary saw cuts are made to a depth terminating short of the active region of the laser chip defined by its heterostructure.