  Herbig Ae/Be (HAeBe) stars have been classified into Group I or Group II,
which were initially thought to be flared and flat disks, respectively. Several
Group I sources have been shown to have large gaps, suggesting ongoing planet
formation, while no large gaps have been found in the disks of Group II
sources. We analyzed the disk around the Group II source, HD 142666, using
irradiated accretion disk modeling of the broad-band spectral energy
distribution along with the 1.3 millimeter spatial brightness distribution
traced by Atacama Large Millimeter and Submillimeter Array (ALMA) observations.
Our model reproduces the available data, predicting a high degree of dust
settling in the disk, which is consistent with the Group II classification of
HD 142666. In addition, the observed visibilities and synthesized image could
only be reproduced when including a depletion of large grains out to ~16 au in
our disk model, although the ALMA observations did not have enough angular
resolution to fully resolve the inner parts of the disk. These results may
suggest that some disks around Group II HAeBe stars have cavities of large
grains as well. Further ALMA observations of Group II sources are needed to
discern how commonly cavities occur in this class of objects, as well as to
reveal their possible origins.
