The characteristics of MOCVD that have taken it
from a research curiosity to production have been in the
simplicity of delivery of the reactive vapors and the versatility
of compositions, dopants and layer thicknesses.
These basic attributes have enabled the same basic technique
to be used for narrow bandgap semiconductors
such as the infrared detector materials CdxHg1−xTe and
GaInSb and now for wide bandgap semiconductors such
as GaN and ZnO. Indeed, the success of GaInN in the
1990s for high-brightness blue LEDs has now led to this
being the most popular material produced by MOCVD.
The early strength of MOCVD was its ability to grow
onto different substrates but this was later abandoned
in favor of the more conventional homoepitaxy; however,
the nitrides rely on heteroepitaxy onto sapphire
and SiC substrates, bringing MOCVD back to its roots
with the early work of Manasevit. This versatility with
substrate materials presents MOCVD with the ultimate
challenge of mating high-performance optoelectronic
materials with silicon substrates in order to combine
the best of optoelectronic and electronic performance.
This section of the chapter will cover the key
elements of the MOCVD process from the physical
characteristics of the precursors through reactor
design to getting the right materials properties for highperformance
devices.