Isolation of p-type carbon δ-doped layers in GaAs by ion bombardment

Abstract

The evolution of the sheet resistance (R s) in δ-doped layers in GaAs during He ion irradiation was investigated. The R s increases with the dose accumulation in a similar way that occurs in layers with much wider dopant profiles, produced either by ion implantation or epi-growth. The R s becomes higher than 10 9 /sq after the so-called threshold dose (D th) is accumulated. The values of D th closely correlate with the ratio of the estimated number of replacement collisions at the depth of the δ-doped layer and the original sheet hole concentration. The maximum thermal stability of the isolation, i.e. the persistence of R s at values above 10 9 /sq after a subsequent thermal annealing is of about 550-600 • C.