On-chip integration of Peltier devices introduces a number of new fabrication considerations and yields a device with increasingly complex operating characteristics, when compared to the discrete device. Due to fabrication compatibility, polycrystalline SiGe (polySiGe) and polycrystalline Si (polySi) are the thermoelectric materials of choice. Device performance is compared for different thermoelectric materials, and the impact of the non-idealities on performance is analysed, interpreting the results in a graphical manner. The primary conclusion from this study is that, although often ignored, the contact resistance of the device is the most prominent non-ideality. Using a fully compatible process, various Peltier devices have been fabricated. The initial values from the measurements performed on both polySi and polySiGe correspond well to those found in literature, validating the design concept, although further optimisation is required.