Thin film transistors (TFTs) including a channel and source/drain that comprise an oxide semiconductor. Oxide semiconductor within the source/drain may be more ordered than the oxide semiconductor within the channel. The localized increased order of the oxide semiconductor may reduce TFT access resistance while retaining good channel gating properties. In some embodiments, order within the source or drain templates from order in adjacent contact metallization. Contact metal at the interface of the oxide semiconductor may be chosen to promote grain growth in the oxide semiconductor during deposition of the oxide semiconductor, or through solid phase epitaxy of the oxide semiconductor subsequent to deposition. Where TFT circuitry is integrated into the BEOL of a CMOS FET IC fabrication process, an EOL forming gas anneal may be employed to both passivate CMOS FETs and crystalize a source/drain of the TFTs.