Developments in atomic layer deposited microchannel plates

Microchannel plate (MCP) imaging electron multipliers are now being manufactured using borosilicate microcapillary array substrates functionalized by the application of resistive and secondary emissive layers using atomic layer deposition (ALD) techniques. Unlike traditional MCP manufacturing, the substrate and the active layers are independent allowing custom nanofabrication and optimization of parameters like gain and resistance through application of high secondary emissive materials. Borosilicate glass substrates are more robust than traditional lead glass MCPs, allowing them to be produced in large formats (400 cm2) with high open area ratios (up to 85%). ALD MCPs have no lead and low alkali metal content, promoting a low intrinsic background (<0.05 events cm−2 sec−1), and have shown stable gain for >7 C cm−2 charge extraction after preconditioning (vacuum bake and burn-in). The UV quantum efficiency of ALD MCPs exceeds conventional MCPs and application of standard alkali halide photocathode layers results in the same improvements expected for MCP devices. The robust nature of ALD MCPs means they can also withstand the processing temperatures required for high temperature deposition of III-V materials, such as Gallium Nitride (GaN), for UV photocathodes with high QEs in the Near-UV (∼200-300nm). Here we present significant progress in the development of ALD MCPs. The newest generation of substrates in 20μm and 10μm pores are more spatially uniform than previous generations, have lower background, and are more stable during life testing. We have tested the QE of bare ALD MCPs and compared them to historical values. We also present the progress of our opaque photocathode deposition efforts.