  We prospose a novel heterostructure system consisting of compounds with
chemical formula A$_2$Mo$_3$O$_8$ (A, B : Zn,Mg,Cd) that can host a two
dimensional electron/hole gas (2DEG/2DHG). We study spontaneous polarization
and piezoelectric properties of these compounds using first principles methods
and Berry phase approach. We show that these kind of heterostructures are very
stable due to extreamly low interfacial strain. The formation of a 2DEG/2DHG
has been investigated in case of Zn$_2$Mo$_3$O$_8$/Mg$_2$Mo$_3$O$_8$ and
polarization discontinuity has been found to be driving mechanism. The sheet
carrier densities and charge localization in these kind of heterostrcutures
have been found to be of the same order of magnitude in other well known system
that hosts 2DEG through similar mechanism, such as AlN/Al(Ga)N or ZnO/Zn(Mg)O.
In addition to conventional applications of a 2DEG, these materials hold
promise to exciting pioneering technolgy such as piezo-phototronics using solar
radiation, as they are also capable of absorbing a significant fraction of it
due to low optical gap of $\sim$ 2 eV
