Deep trench capacitor structures and methods of manufacture are disclosed. The method includes forming a deep trench structure in a wafer including a substrate, buried oxide layer (BOX) and silicon (SOI) film. The structure includes a wafer including a substrate, buried insulator layer and a layer of silicon on insulator layer (SOI) having a single crystalline structure throughout the layer. The structure further includes a first plate in the substrate and an insulator layer in direct contact with the first plate. A doped polysilicon is in direct contact with the insulator layer and also in direct contact with the single crystalline structure of the SOI.