We studied a technique of atomically controlled nitridation doping on GaAs(0 0 1) using (3 x 3) nitrogen (N)-stabilized reconstruction. Ordering of the N-stabilized surface has been found to depend on the (2 x 4)-reconstructed structures of GaAs(0 0 1). Nitridation transforms the (2 x 4) surfaces into the (3 x 3) by way of a new intermediate (3 x 4) surface. From these results, we proposed a model of the nitridation process on the GaAs(0 0 1) surface. Furthermore, layer-by-layer growth of a GaAs-capping layer has been confirmed on the nitrided surface. The atomically doped N-related isoelectronic centers show strong emission lines of excitons bound to N pairs ordered along [1 1 0]. (c) 2006 Elsevier B.V. All rights reserved.