High performance miniaturized InSb photovoltaic infrared sensors operating at room temperature

Abstract

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 (1 0 0) substrate, with a p + - Al x In 1 - x Sb 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 patterned on a 600 × 600 μ m 2 chip. The InSb PVS has a typical responsivity of 1.9 kV/W and an output noise of 0.15 μ V / Hz 1 / 2 . A detectivity of 2.8 × 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 × 2.7 mm × 0.7 mm and to our knowledge is the smallest uncooled sensor for the middle-infrared range reported until now.