Design and development of high quantum efficiency large area UV focal plane arrays for photon counting applications

Abstract

In this paper we will present innovative design approach for UV Focal Plane Array for Photon Counting Applications. This Focal Plane includes the building a large area silicon micro-channel plate (MCP) using GaN photocathode. In this paper, we will present the design and simulation of silicon micro-channel plate with GaN photocathode with large area array with 2 micron pores and 3 micron pitch. We will also present results for the ICP-RIE process to fabricate 2 micron pores, and Growth of high conductivity GaN photocathodes using MOCVD to produce 40% QE.We will also discuss approaches for development of readout architecture and circuit for Silicon based MCP 4096x4096 UV FPA. The readout architecture scheme uses a series of charge sensitive amplifiers (CSA) to boost the charge received on each anode. The signal from each CSA is then passed into a shaping amplifier (SA) that produces a smooth waveform. The peak of the smoothed waveform is captured by a sample and hold (S/H) circuit that holds the signal until an analog to digital (A/D) converter can sample it. Details of the ROIC circuit will be presented.

Activation and evaluation of GaN photocathodes

“…So, they are strongly demanded in UV commnication, UV spectroscopy and other low-light-level UV-imaging applications. The struture of UV image intensifier tubes with GaN photocathode is shown in Figure 1 4 . In electron beam lithography and microscopy there is a pressing need for photocathode that exhibits high quantum efficiency and long lifetime.…”

“…Gallium Nitride (GaN) photocathodes have extensive application from defence, to industrial, to astronomical [1][2][3][4][5][6][7][8][9][10][11] . UV image intensifier tubes with GaN photocathode have higher quantum efficiency, lower dark current, sharper wavelength cut-off response and other characteristics such as solar blind.…”