Development of a 1K × 1K, 8–12 μm QWIP array

Abstract

In the on-going evolution of GaAs quantum well infrared photodetectors (QWIPs) we have developed a 1,024×1,024 (1K×1K), 8–12 μm infrared focal plane array (FPA). This 1 megapixel detector array is a hybrid using an L3/Cincinnati Electronics silicon readout integrated circuit (ROIC) bump bonded to a GaAs QWIP array fabricated jointly by engineers at the Goddard Space Flight Center (GSFC) and the Army Research Laboratory (ARL). We have integrated the 1K×1K array into an SE-IR based imaging camera system and performed tests over the 50–80K temperature range achieving BLIP performance at an operating temperature of 57K. The GaAs array is relatively easy to fabricate once the superlattice structure of the quantum wells has been defined and grown. The overall arrays costs are currently dominated by the costs associated with the silicon readout since the GaAs array fabrication is based on high yield, well-established GaAs processing capabilities. One of the advantages of GaAs QWIP technology is the ability to fabricate arrays in a fashion similar to and compatible with silicon IC technology. The designer’s ability to easily select the spectral response of the material from 3μm to beyond 15μm is the result of the success of band-gap engineering and the Army Research Lab is a leader in this area. In this paper we will present the first results of our 1K×1K QWIP array development including fabrication methodology, test data and imaging capabilities.