Drain Current Of Field Effect Transistor Research Articles

Improvement of the Al2O3/NO2/H-diamond MOS FET by using Au gate metal and its analysis

By using Au as the gate metal contact, performance of NO2-doped H-diamond field effect transistor (FET) has been improved. We fabricated and compared Al2O3 layer deposited, NO2-doped H-diamond FETs with Au, Al and Ti gate metals, respectively. Among them, FET with Au gate metal showed the highest drain current of −61.76 mA/mm, where drain current of FET with Al and Ti gate metals were respectively −42.89 and −39.97 mA/mm. Further, NO2-doped metal-oxide-semiconductor (MOS) structures are fabricated and capacitance-voltage measurements were performed to evaluate the effect of the metal work function and surface barrier height. This phenomenon has been explained in terms of surface barrier height of the Al2O3 layer and metal. Finally, band diagrams of MOS structures are simulated and determined. Band diagrams at various gate voltages are discussed.

Determination of theGe-nanocrystal/SiO2matrix interface trap density from the small signal response of charge stored in the nanocrystals

We investigate the linear response of charge stored in Ge nanocrystals (NCs) embedded in ${\text{SiO}}_{2}$ to an alternating electric field in order to study the electronic properties of the $\text{Ge-NC}/{\text{SiO}}_{2}$ interface. Experimentally, the modulation of the cluster charge is sensed by the transient drain current of field-effect transistors in whose gate oxide the nanocrystals are embedded. For interpretation of the experimental results, we present a small-signal model obtained from a first-order expansion of the general quantum-mechanical description of the system. The contribution of trap states to the alternation of the cluster charge is distinguished from that of quantized states in the NC conduction band by calculating the latter one by density functional theory and subtracting it from the experimental values. A high $\text{Ge-NC}/{\text{SiO}}_{2}$ interface density of $2.8\ifmmode\times\else\texttimes\fi{}{10}^{13}\text{ }{\text{cm}}^{\ensuremath{-}2}\text{ }{\text{eV}}^{\ensuremath{-}1}$ is obtained. These traps cannot be passivated efficiently by a hydrogen anneal at $450\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ and mediate efficient nonradiative recombination processes.