A wide variety of conducting, insulating and semiconducting materials can be deposited using spatial ALD. Examples are AlO, TiO, SiO, HfO, InO, ZnO, ZnO:Al, ZnO:In, IZO, IGZO, ZnSnO, silver and Alucone.
Typical applications are found in the semiconductor and (thin film) photovoltaic industries. An application example is the use of Zn(O,S) buffer layers for CIGS cells.
Currently CdS is the commonly used buffer layer for CIGS cells. However, this material has a number of major drawbacks. Cadmium is a highly toxic material that should be eliminated both from consumer products and from waste streams. Furthermore, the material has a high absorption coefficient in the blue light spectrum, which leads to efficiency loss of the PV modules.
The solution is to replace CdS by ALD deposited Zn(O,S). It completely eliminates the use of toxic cadmium while the improved optical transparency and lower absorption results in an efficiency gain of more than > 0,4% abs.
Moreover, the highly conformal ALD process (without pinholes) opens the opportunity for a simplified CIGS layer build up. At the moment an undoped ZnO layer needs to be deposited to make sure there are no shorts between the AZO and the CIGS materials. This can be omitted with an ALD Zn(O,S) deposited layer.