| AVS 59th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing | Monday Sessions |
| Session EM+TF+OX+GR-MoM |
| Session: | High-k Dielectrics for MOSFETs I |
| Presenter: | X. Qin, The University of Texas at Dallas |
| Authors: | X. Qin, The University of Texas at Dallas B. Brennan, The University of Texas at Dallas H. Dong, The University of Texas at Dallas R.M. Wallace, The University of Texas at Dallas |
| Correspondent: | Click to Email |
Due to the high two-dimensional electron gas (2-DEG) density, AlGaN/GaN high electron mobility transistors (HEMTS) are recognized as key devices for high power and low noise applications. However, the associated large gate leakage current degrades the performance of AlGaN HEMTs. In order to solve this problem, MOS-HEMTs have been developed, in which the incorporation of a high-k gate dielectric layer can overcome the drawbacks.
In this work, the native and treated Al0.25Ga0.75N surface chemical states and structure of were studied by x-ray photoelectron spectroscopy (XPS), ion scattering spectroscopy (ISS) and low energy electron diffraction. Different chemical treatment processes including (NH4)OH, (NH4)2S and HF were studied, followed by atomic layer deposition (ALD) Al2O3 layers on Al0.25Ga0.75N . The oxidation states of the Al0.25Ga0.75Ninterface and Al2O3 deposition process were studied by in-situ XPS analysis. In addition, ex-situ atomic force microscopy (AFM) was used to observe the surface topography before and after the Al2O3 deposition. According to the XPS results, it is found that chemical treatments could remove the native Al2O3 but were not effective to eliminate the Ga oxide, and the growth rate of Al2O3 is low on the native and treated Al0.25Ga0.75N samples. The AFM images show that there are many pin holes in the surface of Al0.25Ga0.75N. Studies of HfO2 deposition will also be presented.
This work is supported by the AOARD under AFOSR Grant No. FA2386-11-1-4077