Formation Techniques Of HgCdTe Dual-band Micro-mesa Arrays

Mercury cadmium telluride(HgCdTe)dual-band infrared detector is one of the most important development trends of 3rd generation infrared detectors.Vertical layer stacking dual-band infrared detectors require high aspect ratio mesas to electrically isolate pixels or trenches to reveal space for shorter wavelength pn diode fabrication.This dissertation focuses on formation techniques of micro-mesa and micro-trench chips,the details are as follows:1.Simulation of I-V characteristics and spectral response of HgCdTe dual-band infrared detector.The dark current characteristics of the device with wide-band graded cap layer are obtained,and the mechanism of how wide-band graded cap layer effectively suppress the surface leakage current of the device was explained.An optimized dual-band device structure with wide-band graded cap layer to have lower dark current level was designed.2.HgCdTe dual-band detector formation techniques.A mask process suitable for low-temperature HgCdTe dry etching was proposed,and ICP etching techniques with high aspect ratio and low damage was established.The aspect ratio was ? 2.6,and the thickness of the etch-induced inversion layer was less than 20 nm.The application of ICP etching technology to etching of the passivation layers before metallization and material surface cleaning are realized.3.Dark current and spectral characteristics of HgCdTe dual-band detectors.The dark current characteristics and spectral response of dual-band devices based on materials with different thermal processes are compared.The dark current of the dualband device matches the simulation results.The dependence between anomal spectral response and the etching depth of dual-band detector chip is established.4.A 30 ?m-pitch,320×256 Mid/Long wavelength simultaneous HgCdTe dualband IRFPA was fabricated,tested and an imaging demonstration were performed.The Mid-wave and Long-wave pixel operability was 91.9% and 96.7% and NETD of 14.9 m K and 59.4 m K,respectively.