Combinatorial Deposition Technique Research Articles

A combinatorial study of SiGeAsTe thin films for application as an Ovonic threshold switch selector

In this paper, we investigate the thermal stability of a wide range of ternary and quaternary (Si)GeAsTe alloy thin films. These type of materials are reported to show Ovonic threshold switching, which means they conduct the current above a specific threshold voltage and are not conducting at lower voltages, making them ideal as a selector element for crosspoint memory devices. For threshold switching to occur in these chalcogenides, the amorphous state of the material is crucial, and hence the material may not crystallize below 400°C to be compatible with temperatures used in device process flows. A combinatorial deposition technique is used to create a thin film library of 36 different compositions, and in situ X-ray diffraction and X-ray fluorescence spectroscopy is used to investigate the thermal stability of the films. We show that Si doping of GeAsTe improves the thermal stability by increasing the crystallization temperature and small amounts of Si (i.e.5at%) decreases the tendency to lose material by sublimation. Also capping the films with a W cap avoids material loss if the capping layer does not show cracking under annealing. An optimal chalcogenide composition, being As50Te20Ge20Si10 combined with a W electrode is identified and is integrated in 65nm mushroom type devices for electrical characterization. The material shows threshold switching and excellent endurance with over 108 cycles.

Colorful solar selective absorber integrated with different colored units.

Solar selective absorbers are the core part for solar thermal technologies such as solar water heaters, concentrated solar power, solar thermoelectric generators and solar thermophotovoltaics. Colorful solar selective absorber can provide new freedom and flexibility beyond energy performance, which will lead to wider utilization of solar technologies. In this work, we present a monolithic integration of colored solar absorber array with different colors on a single substrate based on a multilayered structure of Cu/TiN(x)O(y)/TiO(2)/Si(3)N(4)/SiO(2). A colored solar absorber array with 16 color units is demonstrated experimentally by using combinatorial deposition technique via changing the thickness of SiO(2) layer. The solar absorptivity and thermal emissivity of all the color units is higher than 92% and lower than 5.5%, respectively. The colored solar selective absorber array can have colorful appearance and designable patterns while keeping high energy performance at the same time. It is a new candidate for a number of solar applications, especially for architecture integration and military camouflage.

128 channels of integrated filter array rapidly fabricated by using the combinatorial deposition technique

A combinatorial deposition technique is developed to fabricate integrated narrow bandpass filters (NBPFs) on a single substrate. It is highly efficient for the fabrication of integrated filter arrays in optical regions. An array integrated with 128 NBPFs has been fabricated by using the technique in a nine-step deposition process. The pass bands of the filters distribute almost linearly in the range of 722.0∼880.0 nm. The relative bandwidth of the pass bands is smaller than 0.44%. Such a NBPF array can be utilized as a wavelength division component in many optical applications. It is very powerful for the miniaturization of relevant apparatuses.

Concept of a high-resolution miniature spectrometer using an integrated filter array

A high-resolution miniature spectrometer has been demonstrated by utilizing a 128-channel integrated filter array, fabricated by using the combinatorial deposition technique, as a dispersive component whose passbands range from 722.0 to 880.0 nm with a bandwidth (or spectral resolution) from 1.7 to 3.8 nm and an average channel interval of 1.2 nm. The miniature spectrometer is smaller than 1 cm3 without any moving parts. This kind of miniature spectrometer has the advantages of very low payload, high resolution, and high reliability simultaneously, which are especially urgently needed for space applications.

High growth rate deposition techniques for coated conductors: liquid phase epitaxy and vapor-liquid-solid growth

High growth rate deposition techniques for coated conductors are developed via liquid phase epitaxy (LPE) and vapor-liquid-solid (VLS) growth. By adding fluorine and silver under low oxygen partial pressure, the processing temperature of LPE decreased down to 850/spl deg/C and it enabled us to grow YBCO on metallic substrates such as cube-textured silver tapes. On the other hand, VLS growth is a combinatorial deposition technique between vapor growth and LPE. It is essentially a LPE growth supplied from the vapor phase. Here, we discuss the utilization of VLS growth as a rapid vapor growth for production of YBCO coated conductor.