A straightforward and effective method for the fabrication of double-length-scale patterned (i.e., composite micro- and nanopatterned) carbon nanotube (CNT) arrays can be achieved by block copolymer templating on a prepatterned conducting substrate followed by electroplating to deposit Ni (see figure). Significant improvement in the current density with low threshold voltage and high field-emission efficiency can be found in the composite micro- and nanopatterns of CNT arrays.