The co-doping technique known as an effective method to circumvent the dopant compensation problem was applied for the molecular beam epitaxy (MBE) growth of homoepitaxial ZnTe layers. The co-doping concept is to introduce two oppositely polar atoms at the same time in a 2:1 ratio, forming metastable three-atom complexes located at adjacent crystal sites. Al donor and N acceptor were sandwiched between undoped ZnTe spacing layers. In order to reduce the beam intensity of the RF plasma excited nitrogen species, N-2 gas was diluted by Ar gas. From the low temperature PL spectra, the increase of the Al doping efficiency was confirmed for co-doped layers, especially co-doped using the diluted N-2 gas. (c) 2007 Elsevier B.V. All rights reserved.