Excellent passivation of highly doped p-type Si surfaces by the negative-charge-dielectric Al2O3

From lifetime measurements, including a direct experimental comparison with thermal SiO2, a-Si:H, and as-deposited a-SiNx:H, it is demonstrated that Al2O3 provides an excellent level of surface passivation on highly B-doped c-Si with doping concentrations around 10(19) cm(-3). The Al2O3 films, synthesized by plasma-assisted atomic layer deposition and with a high fixed negative charge density, limit the emitter saturation current density of B-diffused p(+)-emitters to similar to 10 and similar to 30 fA/cm(2) on >100 and 54 Omega/sq sheet resistance p(+)-emitters, respectively. These results demonstrate that highly doped p-type Si surfaces can be passivated as effectively as highly doped n-type surfaces.