Analysis of passivated diamond surface channel FET in dual-gate configuration — Localizing the surface acceptor

The dual gate configuration allows to cascade a Surface Channel MESFET structure with a second MOSFET structure employing the device passivation (ALD-Al2O3) as MOS dielectric. Using the MOS gate as potential probe under drain bias stress, it is possible to identify lateral charge injection from the MESFET gate into the MOSFET gate dielectric. If it can be assumed, that the injected charge neutralizes the acceptor of the surface channel, determining the charge centroid allows to identify the surface acceptor location. In the stress experiment performed, 56% of the channel sheet charge could be neutralized with a charge centroid located within the passivation layer.