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The floating gate type of flash memory is impossible to scale down to beyond 45 nm due to the difficulty in scaling the tunnel oxide and the gate coupling ratio. Because of the difficulty in maintaining high gate coupling ratio and preventing cross talk between neighboring cells, NAND technology is forecasted to migrate gradually from floating gate devices (FG) to charge trapping memory (CTM). CTM...
The leakage current mechanism in Schottky contacts (SCs) to Al0.25Ga0.75N/GaN heterostructures incorporated by thin high-temperature (HT) AlN interlayer has been investigated using current-voltage measurements, atomic force microscopy, and deep level transient spectroscopy. The HT AlN interlayer thickness has a significant effect on the leakage current in SCs. The leakage current density is reduced...
When AlGaN is grown on GaN template, crack networks invariably generate when the thickness of the AlGaN layers over GaN exceeds the critical value. We used thin high temperature deposited AlN layer (HT-AlN) as the interlayer between GaN template and AlGaN epilayer which was very effective in eliminating the cracks in AlGaN epilayer. AlGaN layers with high Al mole fractions were also grown. Characterization...
Morphology and microstructure evolution of Al0.3Ga0.7N epilayers grown on GaN/sapphire templates with low-temperature (LT) AlN interlayers (ILs) by means of metal organic chemical vapor deposition have been investigated by transmission electron microscopy and atomic force microscopy. It is found that the IL improves the surface morphology, and suppresses edge-type threading dislocations (TDs). When...
The physical and electrical characteristics of atomic layer deposited RuO2 nanocrystals embedded in high-?? HfO2/Al2O3 films in an n-Si/SiO2/HfO2/RuO2/Al2O3/Pt memory structure have been investigated. A small size of <10 nm and high-density of ~ 1.6 ?? 1012/cm2 for the RuO2 nanocrystals have been observed by high-resolution transmission electron microscope (HRTEM). The RuO2 metal nanocrystals and...
Enhanced flash memory device characteristics using ALD TiN/Al2O3 nanolaminate charge storage layers have been investigated. After annealing treatment, the TiN nanocrystals embedded in Al2O3 films with a small diameter of ~3 nm and a high-density of >1??1012/cm2 have been formed. The memory devices show a high programming speed of ??Vt >1 V@Vg/Vd=8 V/8 V, 10 ??s and an erasing speed of ??Vt >1...
Performances of AlGaN/GaN HFETs have much improved recently and very high potential of this heterostructure for high power and high frequency electronic devices has been verified. Application of new device technologies such as field plate, recessed gate, digital pre-distortion circuit and dual field plate was essential to realize such high device performances both at 2 GHz, 5GHz and 26 GHz. However,...
The recent discovery of the potential and charge modulation by fluorine ions incorporated in III-nitride heterojunction FETs has opened up numerous new opportunities of realizing desired device performance and fabricating integrated circuits with desirable circuit configurations. The most significant development based on the fluorine plasma ion implantation technology is the demonstration of self-aligned...
GaN/AlGaN device technologies are reviewed aiming at the applications to power switching systems. SL (Super Lattice) capping and QA (Quaternary Alloy) over-layer techniques have been developed to reduce the on-resistance of GaN/ AlGaN HFET. Further, we achieved GaN on Silicon epitaxial growth technology with almost the same mobility keeping the same 2DEG density, which will make the cost comparable...
Magnetotransport study has been performed on AlxGa1-xN/GaN heterostructures at low temperatures and high magnetic fields. The magneto-intersubband scattering effect of the two-dimensional electron gas (2DEG) has been observed in the triangular quantum well at the heterointerface. It is found that the effective mass of the 2DEG have strong dependence on the magnetic field and the 2DEG density due to...
Fluorine plasma ion implantation is a robust technique that enables shallow implantation of fluorine ions into group III-nitride epitaxial structures. This technique has been used to achieve robust threshold control of the AlGaN/GaN high electron mobility transistors (HEMTs) and led to the realization of self-aligned enhancement-mode devices. To reveal the atomic scale interactions and provide a modeling...
To improve the performances of ohmic contacts for GaN devices, a novel multilayer Ti/Al-based metal scheme (Ti/Al/Ti/Al/Ti/Al/Ti/Al/Ni/Au) on undoped AlGaN/GaN heterostructures was employed. A contact with ??c (specific contact resistance) of 8.74E-07 ????cm2, Rc of 0.22 ????mm was demonstrated. Ohmic contacts with the novel metal structure were measured with I-V, SEM, HRTEM to show their properties...
AlGaN/AlN/GaN/InGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) structures with improved buffer isolation have been investigated. The structures were grown by MOCVD on sapphire substrate. AFM result of this structure shows a good surface morphology with the root-mean-square roughness (RMS) of 0.196 nm for a scan area of 5 ??m?? 5 ??m. A mobility as high as 1950 cm2/Vs with...
The influences of applied electrical fields on the absorption coefficient and subband energy distances of intersubband transitions (ISBTs) in AlN/GaN coupled double quantum wells (CDQWs) have been investigated by solving the Schrodinger and Poisson equations self-consistently. It is found that the absorption coefficient of the ISBT between the ground state and the second excited state (1odd-2odd)...
Magnetotransport properties of the two-dimensional electron gas (2DEG) in the triangular quantum well at AlxGa1-xN/GaN heterointerfaces have been investigated by means of temperature dependent Shubnikov-de Haas (SdH) measurements at low temperatures and high magnetic fields under illumination. After the illumination of the heterostructures, the 2DEG concentration increases and the SdH oscillation...
This paper reviews several novel process modules developed for the processing of the backside of the wafer of our substrate-transfer technology called back-wafer-contacted silicon-on-glass (SOG), which is in use for fabricating RF/microwave devices such as high-quality varactors and bipolar transistors. In this technology the silicon wafer is transferred to glass by gluing. The integrity of the acrylic...
Practical and manufacturable solutions for metal gate/dual high-k CMOS integration are presented. In order to overcome the difficulties of threshold voltage control of metal gate/high-k gate stack especially for gate-first integration, several material designs have been proposed so far. These include different metal gate materials and different high-k materials which are separately used in nMOS and...
We summarize our work on creating substrate platforms, processes, and devices for the monolithic integration of silicon CMOS circuits with III-V optical and electronic devices. Visible LEDs and InP HBTs have been integrated on silicon materials platforms that lend themselves to process integration within silicon fabrication facilities. We also summarize research on tensile Ge, which could be a high...
Selective liquid phase oxidation of InGaAs using photoresist or metal as the mask is proposed, and the application of the InAlAs/InGaAs metal-oxide semiconductor metamorphic high-electron-mobility transistor (MOS-MHEMT) is also demonstrated. Without gate recessing, the gate oxide is obtained directly by oxidizing the InGaAs capping layer in a growth solution. Besides, the proposed process can simplify...
We report the successful assessment of both dielectric semiconductor interface, and transistor channel sheet charge densities through the device leakage current characteristics of a MIS GaN HEMT structure. The unconventional test vehicle and procedure described here provide ferroelectric hetero-junction device properties not obtainable using traditional characterization tools.
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