Donor formation in plasma-deposited amorphous silicon (a-Si:H) by erbium incorporation

Erbium-doped amorphous silicon films have been prepared by plasma decomposition of silane doped with the volatile erbium compound tris(2,4-pentanedionato)-Er(III), which has a more favourable erbium–carbon ratio than previously used material. The films exhibit a rather high n-type dark conductivity (σd≈3×10−4 S/cm at T=300 K), a high photoconductivity and a relatively low defect density (ND≈3×1017 cm−3). These properties are similar to those of films doped with approximately 10 ppm phosphine. By co-doping with diborane we obtain compensated (near-intrinsic) a-Si:H(Er) films and p-type samples. These films thus may be suitable for the fabrication of light emitting p–i–n diodes.