Studies of boron on the arsenic site in electron-irradiated GaAs

The introduction of boron on the arsenic site in gallium arsenide, as monitored by the strength of its local vibrational modes (LVM) at 601.7 and 628.3 cm-1, has been observed as a function of 2 MeV electron fluence. Simultaneous monitoring of the strength of the 1S-2P electronic transitions of the neutral shallow acceptors and of the neutral 78 meV acceptor and its singly ionized 203 meV level provides an accurate knowledge of the position of the Fermi level throughout most of the irradiation sequence. The results are inconsistent with previous models for the formation of boron on the arsenic site. We propose a model based on enhanced boron diffusion when the Fermi level lies above 78 meV. A compensation rate for electron irradiation, an introduction rate for the B/sub As/ center, and an infrared cross section for the B/sub As/ LVM are determined