Infrared photodiodes and sensor arrays with improved passivation layers and methods of manufacture

Abstract

InSb infrared photodiodes and sensor arrays with improved passivation layers and methods for making same are disclosed. In the method, a passivation layer of AlInSb is deposited on an n-type InSb substrate using molecular beam epitaxy before photodiode detector regions are formed in the n-type substrate. Then, a suitable P+ dopant is implanted directly through the AlInSb passivation layer to form photodiode detector regions. Next, the AlInSb passivation layer is selectively removed, exposing first regions of the InSb substrate, and gate contacts are formed in the first regions of the InSb substrate. Then, additional portions of the AlInSb passivation layer are selectively removed above the photodiode detectors exposing second regions. Next, metal contacts are formed in the second regions, and bump contacts are formed atop the metal contacts. Then, an antireflection coating is applied to a side of the substrate opposite from the side having the metal and bump contacts. Forming the AlInSb passivation layer before the photodiode detector regions reduces the number of defects created in the n-type InSb substrate during fabrication in comparison to conventional methods and improves the noise performance of InSb photodiodes and sensor arrays incorporating the improved passivation layer.