Amorphous silicon waveguides grown by PECVD on an Indium Tin Oxide buried contact

Low-loss hydrogenated amorphous silicon (α-Si∶H) waveguides were realized by plasma enhanced chemical vapour deposition (PECVD) on a transparent conductive oxide (TCO) layer which is intended to provide the buried contact in active devices, e.g switches and modulators. In particular we propose a technological solution to overcome both the strong reduction in optical transmittance due to the very high extinction coefficient of metal contacts and, at the same time, the optical scattering induced by the texturization effect induced on α-Si∶H films grown on TCO. The realized waveguides were characterized in terms of propagation losses at 1550nm and surface roughness. The experimental performances have been compared to those obtained through calculations using an optical simulation package. The results are found to be in agreement with the experimental data.