Trench capacitors can be formed between lengthwise sidewalls of semiconductor fins, and source and drain regions of access transistors are formed in the semiconductor fins. A dummy gate structure is formed between end walls of a neighboring pair of semiconductor fins, and limits the lateral extent of raised source and drain regions that are formed by selective epitaxy. The dummy gate structure prevents electrical shorts between neighboring semiconductor fins. Gate spacers can be formed around gate structures and the dummy gate structures. The dummy gate structures can be replaced with dummy replacement gate structures or dielectric material portions, or can remain the same without substitution of any material. The dummy gate structures may consist of at least one dielectric material, or may include electrically floating conductive material portions.