Enhanced capacitance trench capacitor

An integrated circuit including a trench capacitor has a semiconductor region in which a material composition varies in a quantity of at least one component therein such that the quantity alternates with depth a plurality of times between at least two different values. For example, a concentration of a dopant or a weight percentage of a second semiconductor material, such as germanium, in a semiconductor alloy can alternate between with depth a plurality of times between higher and lower values. The trench capacitor has an undulating capacitor dielectric layer, wherein the undulations of the capacitor dielectric layer are at least partly determined by the undulating interior surface of the trench. Such trench capacitor can provide enhanced capacitance, and can be incorporated in a memory cell such as a dynamic random access memory ("DRAM") cell, for example.