Abstract
Au-Pt-Ti/high-k/n-InAlAs metal-oxide-semiconductor (MOS) capacitors with HfO2-Al2O3 laminated dielectric were fabricated. We found that a Schottky emission leakage mechanism dominates the low bias conditions and Fowler–Nordheim tunneling became the main leakage mechanism at high fields with reverse biased condition. The sample with HfO2 (4 m)/Al2O3 (8 nm) laminated dielectric shows a high barrier height ϕB of 1.66 eV at 30 °C which was extracted from the Schottky emission mechanism, and this can be explained by fewer In–O and As–O states on the interface, as detected by the X-ray photoelectron spectroscopy test. These effects result in HfO2 (4 m)/Al2O3 (8 nm)/n-InAlAs MOS-capacitors presenting a low leakage current density of below 1.8 × 10−7 A/cm2 from −3 to 0 V at 30 °C. It is demonstrated that the HfO2/Al2O3 laminated dielectric with a thicker Al2O3 film of 8 nm is an optimized design to be the high-k dielectric used in Au-Pt-Ti/HfO2-Al2O3/InAlAs MOS capacitor applications.
Highlights
According to the requirements of high speed, low power dissipation, and low noise application for RF devices used in telecommunication and other modern integrated circuits, increasing interest is focused on new III-V compound devices of InAs/AlSb and InAlAs/InGaAs HEMTs, as these devices possess high electron mobility and peak velocity in the channel [1,2,3,4,5]
HfO2 that presents a high dielectric constant is a popular candidate as the high-k dielectric [8,9,10], it does not match well with InAlAs and the poor lattice match would degrade its performance [9]; Al2 O3 is used frequently as the high-k dielectric as well [10,11], its dielectric constant is not high enough, and that will lead to a lower EOT which is not beneficial for reducing device size
To better understand the generation reason of the leakage current of the Au-Pt-Ti/HfO2 -Al2 O3 /n-InAlAs MOS capacitor, we study the leakage current mechanism of the new devices at different bias condition ranges in detail
Summary
According to the requirements of high speed, low power dissipation, and low noise application for RF devices used in telecommunication and other modern integrated circuits, increasing interest is focused on new III-V compound devices of InAs/AlSb and InAlAs/InGaAs HEMTs (high-electron mobility transistors), as these devices possess high electron mobility and peak velocity in the channel [1,2,3,4,5]. HEMTs [6,7] In this kind of device, InAlAs is most frequently used as the protective layer on the above barrier and as the gate contact semiconductor [1,3], and some reports proposed to deposit a high-k dielectric film on InAlAs, together with the gate electrode, to become a metal-oxide-semiconductor (MOS) capacitor isolated gate structure, in order to effectively suppress the leakage current. In our previous paper [13], the physical and electrical performance of the new Au-Pt-Ti/high-k/n-InAlAs MOS capacitors with HfO2 -Al2 O3 laminated dielectric were studied in detail. As InAs/AlSb HEMTs and InAlAs/InGaAs. HEMTs work under negative gate voltage bias conditions, we studied the reverse-bias leakage current mechanism in this paper as in the case of a real application
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