English: A scientist holding a 4 inch diameter n-type float-zone silicon wafer that has been through PECVD to coat a thin film (tens of nanometres) of amorphous silicon onto it. This creates a passivation layer such as what is used in silicon heterojunction solar cells. Typically, high quality amorphous layers in a SHJ solar cell would be on the order of less than 10 nm. However the thin film is thicker for this research cell due to technical limitations (50–200 nm). This research cell was used to research how high temperatures affect the passivation layer of heterojunction solar cells.