An Atomic Layer Deposition Method to Fabricate Economical and Robust Large Area Microchannel Plates for Photodetectors

We demonstrate an economical and robust route to fabricate large-area microchannel plate (MCP) detectors which will open new opportunities in larger area MCP-based detector technologies. Using our newly developed bottom-up process flow, we have fabricated large area MCPs (8 x 8). We used Atomic Layer Deposition (ALD), a powerful and precise thin film deposition technique, to tailor the electrical resistance and secondary electron emission (SEE) properties of large area, low cost, borosilicate glass capillary arrays. The self limiting growth mechanism in ALD allows atomic level control over the thickness and composition of resistive and secondary electron emission (SEE) layers that can be deposited conformally on high aspect ratio capillary glass arrays. We have developed several robust and reliable ALD processes for the resistive coatings and SEE layers to give us precise control over the resistance in the target range for MCPs (106-109 Ω) and SEE coefficient (up to 8). The MCPs are tested in stacks of one or two plates and exhibit gains as high as 107 for a pair of MCPs. This approach allows the functionalization of microporous, insulating substrates to produce MCPs with high gain and low noise. These capabilities allow separation of the substrate material properties from the amplification properties. We studied the various MCP parameters such as gain, background counts, and resistance as a function of the ALD process parameters. Here we describe a complete process flow to produce fully functionalized working large area MCPs.