P-Type δ-Doped Layers in GaAs Isolated by He+ Bombardment

Abstract

Ion implantation is an essential process for production of modern III-V compound semiconductor devices and circuits and has been proven as a successful method to convert a conductive layer into a highly resistive one. Due to its simplicity, precise depth control and compatibility with planar technologies, ion implantation is a potential alternative for mesa etching. Selective masking of the semiconductor surface with photoresist followed by ion irradiation is an efficient and practical way to isolate closely spaced devices. Irradiation of GaAs by ions results in resistivity increase as a consequence of free carrier removal by trapping at defects introduced by the irradiation. Delta-doping is a well known technique which spatially confines the dopants to one atomic layer during epitaxial growth of semiconductor materials. In the present work a dose dependence of sheet resistance of delta- doped GaAs structures, irradiated by He+ ions, was inve stigated. It was found that a threshold dose for electrical isolation of the structures was determined by the energy of ions and by the concentration of initial doping.