The Collapse of p-type Mobility in the Amorphous Phase

Many electronic applications such as optically transparent electronics, back-end-of-line applications, monolithic 3D stacking, and flexible electronics require the enablement of both n- and p-type transistors deposited at moderate temperatures. Identifying materials with high charge carrier mobility that are compatible with this constraint is challenging, as most materials have crystallization temperatures that exceed this range. For n-type materials, one approach is to use amorphous semiconductor oxides. In this Letter, we evaluate materials, predicted to be good candidates as a p-type in the crystalline phase, for their ability to keep their properties in the amorphous phase. We show that none of these are expected to outperform amorphous silicon, which has already too low charge carrier mobility. The focus of further research will hence need to be on finding materials with a low crystallization temperature or on finding deposition strategies that allow for the deposition of crystalline layers directly under moderate conditions.