Liquid cyclohexasiloxane (CHS) is a clear colorless liquid with a boiling point of 80°C at 10-15 torr and a melting point of ~ 18°C. As a liquid, the CHS monomer can be used in printing applications to create diodes or thin film transistors with dimensions as low as 5 microns, doped for p and n-type Si, used to create large area thin films by solution processing, or electrospun into nanowires.
The liquid is stable at 100°C for at least 12 hours and loses hydrogen rapidly above 220°C as it converts to amorphous silicon. This low temperature conversion allows the use of a broad range of substrates when designing printable electronics. With further heat treatment the amorphous silicon can be transformed into crystalline silicone.
The resulting silicon has superior and proven electronic characteristics when compared to organic semiconductors allowing for improvements in the performance of printable electronics.The liquid “neat” ink has improved shelf life when compared to doped Si-nanoparticle filled liquid silanes commonly used for printable electronics. CHS and its formulations can easily be electrospun into silicon nanowires as a lower cost alternative to vapor-liquid- solid growth processes or etching of silicon wafers. CHS has also been coated onto graphene or carbon with subsequent conversion into silicon carbide.
As a gas, CHS can be used to replace more traditional silanes used in the electronics industry during plasma-enhanced chemical vapor deposition (PECVD). Key advantages of CHS as a PECVD precursor include the simultaneous delivery of 6 Si atoms into the PECVD chamber thus enabling higher deposition rate, increased safety due to the low vapor pressure at room temperature of CHS (0.3 torr), absence of the need for dilution during process, and elimination of a costly multistage purification process when used for thin film deposition.