Orientation dependence of the aluminum concentration in AlxGa1−xAs epilayers grown by molecular beam epitaxy on a nonplanar substrate

Advances in crystal growth technology have led to increased control of the crystal composition during the growth process. An example of this is the monolayer precision with which the composition of semiconductor crystals can be varied using molecular beam epitaxy (MBE). Since MBE growth on planar substrates affords control of the composition only along the growth axis, additional processing is required to introduce lateral variation of the crystal properties. The use of nonplanar substrates produces lateral variations in the properties of crystalline layers grown by MBE, adding a new dimension to the power of MBE as a tool for device fabrication.1–4 For example, growth on nonplanar substrates has been used for the fabrication of buried heterostructure quantum well lasers in a single growth step3, and it has been proposed as a technique for the fabrication of quantum wire lasers.3,4