The transport and isolation properties of polycrystalline GaAs selectively grown by molecular beam epitaxy

Selective-area polycrystalline GaAs using SiO2masking is planarly grown by molecular beam epitaxy (MBE). The electric properties of the polycrystalline GaAs are investigated because this technology is very promising for device isolation in GaAs integrated circuit and electro-optic integration. Compared with the isolation characteristics of semi-insulating GaAs, polycrystalline GaAs has similar low-field resistivity, higher high-field leakage current, and no well-defined trap-fill-limited voltage. The grain boundary (GB) states of polycrystalline GaAs trap negative charge that builds up a potential barrier to hinder electron current. The GB density of states profile estimated from the IV characteristics shows a peak value 5 × 10¹²cm^-2.eV¹and a wide energy distribution, 0.33 eV above the equilibrium Fermi energy.