Micro-spectrometer based on 64-pixel high-sensitivity quantum dot detector array

A high photoexcited carrier multiplication photodetector operating at room temperature is reported. The device is a GaAs n-i-n photodetector with double-barrier AlAs in which a thin quantum well contains a mixture of quantum dot (QD) structures. This special structure makes the proposed photoelectric detector have high sensitivity to light under an operating temperature of 300 k. Its current responsivity can reach about 7 × 10¹¹ A/W with 0.01 picowatts 633 nm light power and -0.5 V bias. The response voltage is 7 mV at an integration time of 80 μs. The voltage responsivity reached about 2.7 × 10⁹ V/W. An embedded micro-spectrometer based on the high-sensitivity features of the photodetector has also been designed. By means of QD fluorescent sample testing and comparison, the proposed spectrometer is found to have higher sensitivity and a shorter integration time than the `NOVA´ spectrometer (product model of the spectrometer of ideaoptics, China) based on a backside-illuminated CCD (Hamamatsu, S7031-1006S). The QD spectrometer was mounded in a hyperspectral microscopy imaging system with an optical path switcher. The system has been used to analyse and to make a comparative study of the biological section. This kind of spectrometer with highly sensitive linear QD detectors has good application prospects in the fields of biological science, medical diagnosis and environmental detection.