Synthesis, Characterization, and Application of Tunable Resistance Coatings Prepared By Atomic Layer Deposition

Abstract

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W:Al2O3 Nanocomposite Thin Films with Tunable Optical Properties Prepared by Atomic Layer Deposition

“…ALD is a powerful method for precisely doping thin film materials because the film growth is mediated by self-limiting surface chemical reactions and not by the fluxes of the incoming species. , This provides precise control over the film thickness and also very conformal coating over high aspect ratio 3D structures. , More importantly for this study, the self-limiting growth yields exquisite control over composition by alternating between the chemistries of two or more ALD materials in a controlled fashion. − The ALD of W:Al 2 O 3 mixed layers has been previously demonstrated in the form of both nanocomposites and nanolaminates. − The ALD W:Al 2 O 3 nanolaminate films have been implemented as hard X-ray mirrors , and thermal barrier coatings . The ALD W:Al 2 O 3 nanocomposite films have been utilized as tunable resistive films , where the film resistivity can be varied by orders of magnitude by adjusting the W cycle percentage. Tunable resistive films composed of both ALD W:Al 2 O 3 and Mo:Al 2 O 3 nanocomposite layers have been used to manufacture large area microchannel plates and electron optical MEMS devices. − To date, the optical properties of the ALD W:Al 2 O 3 nanocomposites have not been explored.…”

“…14−19 The ALD W:Al 2 O 3 nanolaminate films have been implemented as hard X-ray mirrors 17,18 and thermal barrier coatings. 15 The ALD W:Al 2 O 3 nanocomposite films have been utilized as tunable resistive films 14,19 where the film resistivity can be varied by orders of magnitude by adjusting the W cycle percentage. Tunable resistive films composed of both ALD W:Al 2 O 3 and Mo:Al 2 O 3 nanocomposite layers have been used to manufacture large area microchannel plates and electron optical MEMS devices.…”

A Brief Technical History of the Large-Area Picosecond Photodetector (LAPPD) Collaboration

“…For each goal we have tabulated the LAPPD papers published describing the results of the R&D. A discussion of the successes and failures is given in Section 6. Goals: Microchannel Plates Goal References Suitability (uniformity, open-area, manufacturability) of drawn glass capillary substrates as MCP's [27,28] Suitability (uniformity, open-area, manufacturability) of AAO etched aluminum substrates as MCPs [29] Down-selection decision between glass and AAO substrates NA Development of Atomic Layer Deposition Resistive coatings [30,31,32] Development of Atomic Layer Deposition secondary-emitting coatings [33,34,34,35,36,37] Development of high-yield manufacturing techniques for 8" glass substrates [27,28] Implementation of facilities for characterization of the 8" LAPPD TM MCPs for robustness, gain, uniformity, life-time, and time and position resolution [38], [39] Table 1. The goals (Column 1) and published references (Column 2) for achievements of the LAPPD Microchannel Plate Group.…”

“…The plot shows the exponential behavior versus the number of metal cycles, a mixed blessing in that the behavior allows covering a large range, but also has a high sensitivity to the metal content. The resistivity of the molybdenum films is more sensitive to the metal cycle percentage than that of the tungsten films because the amount of Mo deposited in a single Mo ALD cycle is approximately twice that of the W ALD [30,31] The emission of secondary electrons versus electron energy is an essential input into simulations of the cascade in the capillary pores, used to predict the voltage needed, gain, and pulse behavior [51,36]. A dedicated facility for the measurement of secondary emission yield (SEY) vs incident electron energy was constructed in the Materials Science Division (MSD) at ANL.…”

“…We encountered many industrial 'recipes' ripe for a deeper understanding of the underlying material science, chemistry, and physics. LAPPD has consequently put a high premium on publishing technical details of the development, including papers on the glass/ALD MCPs [29,30,31,32,51,36,37,33,83], fast timing and electronics [38,46,84,45,53], and packaging [39,44,45,27,28]. Conference reports from throughout the R&D can also be found in the Document Library.…”