THE CURRENT–VOLTAGE CHARACTERISTICS OVER THE MEASUREMENT TEMPERATURE OF 60–400 K IN THE Au/Ti/nn-GaAs CONTACTS WITH HIGH DIELECTRIC HfO2 INTERFACIAL LAYER
Abstract
The Au/Ti/HfO2/nn-GaAs metal/insulating layer/semiconductor structures have been fabricated using standard thermal atomic layer deposition. We experimentally showed whether or not the HfO2 interfacial layer grown on the nn-GaAs wafer modifies the barrier height (BH) of the device at the room temperature. Besides, we investigated the measurement based on temperature dependence of the device parameters from the current–voltage (II–VV) characteristics of the diode in 60–400K range with steps of 10K. The X-ray photoelectron spectroscopy (XPS) have been carried out to characterize the surfaces of both nn-GaAs wafer and HfO2 thin films. The series resistance value from the temperature-dependent II–VV characteristics decreased with decreasing temperature, which is a desired positive result for the devices developed from the MOS capacitor. The BH value of 0.94eV (300K) has been obtained for the device with the HfO2 layer which is a higher value than the value of 0.77eV (300K) of the device without HfO2 layer. Therefore, we can say that the HfO2 thin layer at the metal/GaAs interface can also be used for the BH modification as a gate insulator for GaAs MOS capacitor and MOSFETs. When the temperature-dependent II–VV characteristics at low temperatures have been considered, it has been observed that the current prefers to flow through the lowest BHs due to the BH inhomogeneities.
