Thin Film Deposition Applications
Thin film deposition systems based on several technologies have been installed at several laboratories worldwide (Reference List) A wide range of materials has been deposited in the systems delivered by Elettrorava; in particular several research projects have been conducted in cooperation with some of our key customers, involving deposition and optimization of intrinsic and doped amorphous and microcrystalline silicon and silicon alloy materials, diamond-like carbon and diamond films and optical multilayer devices: a summary of the main results is reported.
The extensive solar cell research program carried out at Utrecht University has allowed to deposit by PECVD devices with efficiencies in excess of 10%. A HWCVD chamber on the multichamber system has allowed to optimize deposition of amorphous and polycrystalline silicon thin films deposited by HWCVD and to produce highly stable pin devices.
Extensive research programs have been carried out on the PECVD multichamber system installed at the IMM-CNR laboratory in Bologna on the ECR-PECVD/RF-PECVD two chamber system installed at Politecnico di Torino and on the PECVD system delivered to Università di Napoli and have led to scientific results reported in many papers. The main topics investigated and the main results obtained are summarized here.
Deposition of silicon carbide alloys using RF-PECVD: the optoelectrical properties of amorphous silicon carbide have been optimized for films deposited in gas mixtures of silane and methane/acetylene both undiluted and with the addition of hydrogen (hydrogen diluted gas mixtures). It has been shown that the energy gap can be varied in a wide range and that hydrogen dilution improves the optoelectrical properties for films with high values of the energy gap. Deposition of silicon nitride alloys using RF-PECVD: the optoelectrical properties of amorphous silicon nitride have been optimized for films deposited in gas mixtures of silane and ammonia both undiluted and with the addition of hydrogen (hydrogen diluted gas mixtures).
It has been shown that the energy gap can be varied in a very wide range and that hydrogen dilution improves the optoelectrical properties for films with high values of the energy gap. Deposition of silicon and its alloys using VHF-PECVD: amorphous silicon, silicon carbide and silicon nitride alloy films have been deposited at 100 MHz. These films are deposited at a high deposition rate and at the same time show good optoelectrical properties. Deposition of multilayer structures: multilayer structures consisting of alternate high energy gap and low energy gap layers have been deposited; these structures show good photoluminescence properties.
Deposition of heterojunction solar cells: intrinsic and doped amorphous silicon layers have been deposited on crystalline silicon wafers in order to produce photoelectrically active pin devices with good optoelectrical quality. Deposition of LED’s: LED’s using as active layer amorphous silicon carbide and silicon nitride layers as well as multilayers have been deposited; these devices show good emission in the visible spectrum.