Design and characterization of superlattice infrared photodetector operating at low bias voltage

In this paper, we investigate the performance and characterization of a 15- period superlattice embedded between two thick AlGaAs barriers. The structu re can operate at low bias voltage with less power consumption for 8-10 mu m long-wavelength infrared detection. In our design, one barrier is used to reduce the dark current and the other one is designed to enhance the colle ction efficiency of photoelectrons at the collector contact, The fabricated detector can be operated at a bias voltage lower than 0.1 V and exhibits p ronounced photovoltaic response. The spectral response shows voltage depend ence around 0 V, At high bias voltage (>25 mV) the spectral lineshape is in dependent of bias and is around 8-10 mu m with peak wavelength at 9.3 mu m. At lower bias voltage the response is shifted toward shorter wavelength ra nge. The peak responsivity was found to be 12 mA/W at lambda(p) = 8.7 mu m and zero bias and 85 mA/W at lambda(p) = 9.3 mu m and 0.1 V,Background limi ted can be achieved up to 65 K with bias, voltage less than 0.1 V,The measu red noise power spectral density of the dark current at 77 K shows the char acteristics of full shot noise rather than the generation-recombination noi se. The peak detectivity is determined to be D* = 3.5 x 10(9) cm root Hz/W at 77 K and 0.1 V. In comparison with a conventional 30-period QWIP, our de tector has the advantages of better performance at low bias voltages with l ower power consumption and a tunable feature of spectral range.