A miniaturized InSb photovoltaic infrared sensor (InSb PVS) that operates at room temperature was developed. The InSb PVS consists of an InSb p(+)-p(-)-n(+) structure grown on semi-insulating GaAs (100) substrate, with a p(+)-AlxIn1-xSb barrier layer between p(+) and p(-) layers to reduce diffusion of photoexcited electrons. We found the optimum Al composition and thickness of AlInSb barrier layer to be x = 0.17 and 20 nm, respectively. To improve the signal-to-noise ratio of InSb PVS, 700 serially connected photodiodes were 1/2 patterned on a 600 x 600 mu m(2) chip. The InSb PVS has a typical responsivity of 1.9 kV/W and an output noise of 0.15 mu V/Hz(1/2). A detectivity of 2.8 x 10(8) cmHz(1/2)/W was obtained at 300 K. The InSb PVS was flip-chip bonded on a pre-amplifier IC and finally encapsulated by a dual flat non-leaded (DFN) package with a window, which exposes the backside of the GaAs substrate allowing the infrared light incidence. The device external size is 2.2 mm x 2.7 mm x 0.7 mm and to our knowledge is the smallest uncooled sensor for the middle-infrared range reported until now. (c) 2006 Elsevier B.V. All rights reserved.