Described herein are methods and structures integrating one or more TMDC crystal heteroepitaxially grown on one or more group III-Nitride (III-N) crystal. The TMDC crystal may be grown on a III-N heteroepitaxial crystal that has been grown on crystalline silicon substrate. One or more of III-N devices and silicon devices employing separated regions of the heteroepitaxial substrate may be integrated with a TMDC device fabricated on with the TMDC crystal. In some embodiments, impurity-doped III-N source/drain regions provide a low resistance coupling between metallization and a TMDC-channeled transistor.