Cluster deposition tool (CT1)
The cluster tool is a computer controlled four chamber system for the chemical vapor deposition of amorphous (a-Si:H) and microcrystalline (µc-Si:H) silicon and silicon alloys (SiC:H and SiOx:H). The four chambers surround a central transfer chamber. A robot handles the sample transfer between the chambers.
Three chambers are used for plasma enhanced chemical vapor depositions (PECVD). One of the chambers is used exclusively for intrinsic silicon absorber layers. Phosphine and trimethylborane are used as doping gases in the other two PECVD chambers. These two chambers are equipped with premix chambers. The plasma frequencies in all three PECVD chambers can be set to the RF (13.56 MHz) or the VHF range.
As a fourth chamber, the system provides a hot-wire chamber. During the hot-wire deposition (also known as catalytic chemical vapor deposition), a hot wire from tantalum, tungsten, or rhenium decomposes the process gas molecules. This technique allows the deposition of thin films with improved properties for the use in solar cells, which leads e.g. to an increase in open circuit voltage VOC of the solar cells.
- Amorphous (a-Si:H) and microcrystalline (µc-Si:H) pin solar cells
- Tandem cells from a-Si:H/µc-Si:H (pin-pin arrangement)
- Flexible solar cells on foil substrates
- Depositions at high plasma power for increased deposition rates
- Passivation and contact layers for heterojunction solar cells
- Hot wire deposited Si and SiC films