Flatband Voltage Instability Characteristics Of Hfo2-Based Gaas Metal-Oxide-Semiconductor Capacitors With A Thin Ge Layer

This work investigates the flatband voltage instability of HfO2-based GaAs metal-oxide-semiconductor (MOS) capacitor with a thin germanium (Ge) interfacial passivation layer (IPL). Both positive and negative dc gate biases are used as stress condition. By studying various samples such as the devices with extremely thin equivalent oxide thickness of 8.7 A, with optimum, thick Ge IPLs, and without Ge IPL at a given HfO2 thickness, as well as the devices with varying thicknesses of HfO2 on the optimum Ge IPLs, it is found that both the interface trap and the bulk trap of HfO2 are crucial in affecting the flatband voltage instability characteristics of HfO2 GaAs MOS capacitors. The results indicate that the minimum flatband voltage instability requires a higher quality interface and a thinner HfO2 layer, which can be achieved by employing Ge IPL technique in GaAs system. (c) 2008 American Institute of Physics.