This MRS Proceedings book contains the papers presented in Symposium 7E: "Low-Dimensional Semiconductor Structures" at XXII International Material Research Congress, IMRC 2013, and in Symposium 6B: "Low-Dimensional Semiconductor Structures" at XXI International Material Research Congress, IMRC 2012, which were held in Cancun, Mexico on August 11-15, 2013 and August 12-16, 2012, respectively.