All the techies on this forum already knows about what is explained in this WP just like the semiconductor 101 presentation I recently shared (see the link library).

And although, some of them have multiple times "digested" the technical information for us, the non-techies, this White Paper (which is not from POET) is an interesting read (IMO).

Abstract:

This paper describes the past quarter century’s history of developing various kinds of compound semiconductor substrates, epitaxial growth technologies, and optical and electron devices, focusing mainly on Sumitomo Electric’s research and development activities. Semiconductor structures with desirable properties can be obtained by distributing multiple compound semiconductors three-dimensionally according to the design, and innumerable compound semiconductor devices with a variety of functions and characteristics can be achieved. This is a magnificent feature and great magnetism unique to compound semiconductors and not found in silicon semiconductors.

It is an issue, engineering issue, that the three-dimensional distribution of compound semiconductors can be formed according precisely to the design.

http://global-sei.com/tr/pdf/special/72-01.pdf