Third-generation infrared detector program at SCD: InAlSb focal plane arrays

Antimonide Based Compound Semiconductors (ABCS) and a new family of advanced analogue and digital silicon read-out integrated circuits form the basis of the SCD 3rd generation detector program, which builds on the firm platform of SCDs existing InSb-FPA technology. We have devised a staged roadmap at SCD which begins with epitaxial InSb mesa diodes and gradually increases in technological sophistication. In the initial stages we have focused in particular on In 1-z Al z Sb alloys grown on InSb by Molecular Beam Epitaxy (MBE). Some of our achievements with these materials are presented in this paper. For epitaxial InSb (z = 0), we demonstrate the performance of Focal Plane Arrays (FPAs) with a format of 320x256 pixels, at focal plane temperatures between 77K and 110K. An operability has been achieved which is in excess of 99.5%, with a Residual Non-Uniformity (RNU) at 95K of less than 0.03% (standard deviation/dynamic range) between 15 and 80% well fill. Moreover, after a two point Non-Uniformity Correction (NUC) has been applied at 95K, the RNU remains below ~0.1% at all focal plane temperatures down to 85K and up to 100K without the need to apply any further correction. This is a major improvement in both the temperature of operation and the temperature stability compared with implanted diodes made from bulk material. We also demonstrate rapid progress in the development of epitaxial InAlSb FPAs with comparable operability and RNU to the InSb FPAs but which exhibit lower dark current and offer a range of cut-off wavelengths shorter than in InSb. These FPAs are intended for temperatures of operation in excess of 100K.