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.