Monolithic
integration of wurtzite III-nitrides with nonpolar silicon
(Si), the two most-produced semiconductor materials, is essential
and critical for a broad range of applications in electronics, optoelectronics,
quantum photonics, and renewable energy. To date, however, it has
remained challenging to achieve III-nitride heterostructures on Si
with controlled lattice-polarity. Herein, we show that such critical
challenges of III-nitrides on Si can be fundamentally addressed through
a unique interfacial modulated lattice-polarity-controlled epitaxy
(IMLPCE). It is discovered that the lattice-polarity of aluminum nitride
(AlN) grown on Si(111) is primarily determined by the AlSiN interlayer:
N-polar and Al-polar AlN can be achieved by suppressing and promoting
the AlSiN interlayer formation, respectively. Furthermore, we develop
a unique active-nitrogen-free in situ annealing process
to mitigate the AlSiN layer formation at the GaN/AlN interface, which
can eliminate the inverted domain formation commonly seen in N-polar
GaN on AlN/Si. This study provides an alternative approach for controlling
the lattice-polarity of III-nitrides on Si substrates and will enable
their seamless integration with the mature Si-based device technology.