In < Sub > 0.17 < / Sub >, < Sub > 0.83 < / Sub > N/gan Heterostructure Thermal Oxidation Characteristics Of The Study

Owing to the outstanding physical and chemical properties, InAlN/GaN based high electron mobility transistors (HEMTs) have appeared as very attractive candidates for high temperatures, high voltage and high power applications in the millimetre-wave range. Nevertheless, InAlN/GaN HEMTs suffer from relatively extensive gate leakage currents and current collapse, which could however be reduced by the insertion of a thin dielectric layer. The Al-rich In0.17Al0.83N alloys are very easy to be oxidized. Thus, the "nearly native" Al2O3oxide layer will be formed on the surface by means of the thermal oxidation at more than800℃in oxygen atmosphere. That is essential for the InAlN/GaN MIS devices prepared. Unfortunately few studies have been concentrated on the tehermal oxidation of InAlN/GaN.heterostructue. As a result, in this paper the focus is the characteristics of Al-rich In0.17Al0.83N/GaN heteroj unction structure of the thermal oxidation. The main contents are as follows:1. The chemical bonding states and the intesnsity of Al2O3and AlN were characterized by X-ray photoelectron spectroscopy(XPS) on different In0.17Al0.83N surfaces which were oxidated under different oxidation conditions in O2atmosphere or just had been placed in the air for several weeks after deposited by MOCVD. Then, the oxide thickness was obtained. The oxidation process is analyzed according to the diffusion theory. Thus the relationship between the oxide thickness and oxidation time is derived. Then the surface oxide thickness datas rising from the XPS analysis and the theoretical derivation were compared with the help of MATLAB software. The results show that the experientally measured oxide thickness datas and the theoretical results are consistent after a certain oxidation time.2. The Raman spectrum of different samples which are oxidated under different oxidation conditions in O2atmosphere or just had been placed in the air for several weeks after deposited by MOCVD were discussed. The L+mode is utilized to study the relationship between the two-dimensional electron gas (2DEG) concentration and the thickness of In0.17Al0.83N or the surface oxide. The L+mode is only observed on the surface of unintentional oxidation in the thickest sample, which indicates that the2DEG concentration of this sample is the largest among those samples.3. The2DEG concentration is formulated in the oxide/(InAlN/GaN heterostructure) system. And much attention is paied to the impact of surface oxide on the2DEG concentration. It is found that the oxide/InAIN interface charge(Nint), the potential difference (ΦB-ΔEcIIns), the oxide thickness and the In0.17Al0.83N thickness are the key factors to2DEG concentration. In addition, the MATLAB software is used to simulate2DEG concentration, which vividly demonstrates the effect of these factors on the2DEG concentration.