In Be delta-doped GaAs structures grown by molecular beam epitaxy, a transition from thermally activated conduction to metallic conduction occurs at room temperature, where the sheet resistance of a sample at the transition is close to the quantum unit of resistance 1/2h/e(2), 12.9k ohm. The metal-insulator transition phenomenon in these structures is analyzed with a model in which a large number of quantum point contacts with random channel energies form a network. A number of experimentally observed features such as the sheet resistance at She transition and direct correlation of the activation energy for the conduction to the density of states in the quasi-two-dimensional hole system can be explained by the model. The formation of individual quantum point contact structures is analyzed by molecular dynamic simulations of Be atom distributions in a delta-doped layer. (c) 2007 Elsevier B.V. All rights reserved.