A low-temperature CVD oxide process for inversion layer-MIS solar cells

This paper discusses the use of low temperature chemical vapor deposition of silicon dioxide for inducing the inversion layer in an IL-MIS silicon solar cell. Measured physical (refractive index, dielectric constant, etch rate) and electrical (oxide charge, surface states) parameters are presented to show the suitability of CVD oxides for this application. Evidence is presented supporting a Siⁿ⁺trapping model as the source of the oxide charge. Dark current results are presented for MIS diodes, with and without surrounding inversion layers. These show that the inversion layer adds a component of current to the MIS diode current when it is in electrical contact with the inversion layer under the minority carrier MIS diode. Combining a CVD oxide induced inversion layer with an MIS grid is shown to be capable of yielding high efficiency solar cells prepared at temperatures below 350°C.