For the infrared detection in the 3-5 μm range, p-GaAs/Al_xGa_1-xAs heterojunction is an attractive material system due to light hole/heavy hole and spin-orbit split-off intra-valance band transitions in this wavelength range. Varying the Al mole fraction (x) provides the tuning for the wavelength threshold, while graded Al_xGa_1-xAs potential barriers create an asymmetry to allow a photovoltaic operation. The photovoltaic mode of operation offers the advantage of thermal noise limited performance. In our preliminary work, a 2 – 6 μm photovoltaic detector was studied. Implementation of an additional current blocking barrier improved the specific detectivity (D*) by two orders of magnitude, to 1.9×10¹¹ Jones at 2.7 μm, at 77K. At zero bias, the resistance-area product (R₀A) had a value of ~ 7.2×10⁸ Ω cm², which is five orders higher in magnitude (with a corresponding reduction of the responsivity by only a factor of ~ 1.5), compared to the R₀A value without the blocking barrier. A photoresponse was observed up to 130K.

Date Published: 3 February 2017
PDF: 7 pages
Proc. SPIE 10036, Fourth Conference on Sensors, MEMS, and Electro-Optic Systems, 1003615 (3 February 2017); doi: 10.1117/12.2242898

Published in SPIE Proceedings Vol. 10036:
Fourth Conference on Sensors, MEMS, and Electro-Optic Systems
Monuko du Plessis, Editor(s)