Considerable effort is being made to grow controlled thin layers of a variety of semiconductors and other type of materials. These have been of increasing importance in the fabrication of both electronic devices and optoelectronic devices and will see increasing importance in the future. Along with the ability to fabricate the layers it would be advantageous to be able to write patterns in situ, that is while the layers are being grown. This proposal addresses problems associated with such patterning.
