Low-light-level readout of a new quantum dots sensor at room temperature

In this paper, we present an approach for low-light-level detection based on quantum dots and quantum well(QW) hybrid structure sensor operating at room temperature. The photodetector has AlAs/GaAs/AlAs double barrier structures with a layer self-assembled InAs quantum dots(QDs) and In_0.15Ga_0.85As QW. The photodetector shows high sensitivity to weak light irradiation and the operating temperature at 300 K. Its photoexcited carrier multiplication factor can reach about 2.35 × 10⁶ at 0.01 picowatts (pW) 632.8 nm light power and −0.5 V bias. And the response voltage is 7−mV at integration time 80 μs. This high multiplication factor is achieved by the InAs QDs and In0.15 Ga0.85As QW induced photovoltaic effect. A high sensitivity micro spectrometer based on the 64 pixels QDs photodetector linear array was developed. The novel micro spectrometer was used to investigate the biological sample. The test results show the spectrometer based on QDs photodetector has higher sensitivity contrast with commercial spectrometer. The high sensitivity features of the spectrometer make it a promising choice for Raman or fluorescence detection.