We report using a novel weak-oxidant plasma-enhanced atomic layer deposition (PEALD) process at 200 ??C to deposit ZnO thin films for stable, high mobility, pyroelectric thin film transistors (TFTs). Our PEALD ZnO TFTs use Al2O3 gate dielectric, also deposited by PEALD, and have field-effect mobility of 20-30 cm2/V-s. In these ZnO TFTs the mobility is found to be very weakly temperature activated (< 10 meV) down to 77 K, but the devices have a fast, linear, and reversible, threshold voltage shift with temperature which is believed to be related to pyroelectric charge in the ZnO layer.