Abstract
The capacitance–voltage characteristics of metal–insulator–semiconductor structures based on Hg1−xCdxTe (x = 0.218) with CdTe passivation are studied before and after the passivation annealing process. We found that after vacuum annealing at 300 °C for 24 h, the micromorphology of the passivation layer was significantly improved, and as the fixed charge density decreased from 1.3 × 1012 cm−2 to 1.0 × 1010 cm−2, the fast surface state density decreased from 2 × 1013 cm−2 eV−1 to 3 × 1012 cm−2 eV−1, with a minimum value of 1.2 × 1011 cm−2 eV−1. From these findings, combined with the secondary ion mass spectroscopy analysis, we conclude that the annealing process propagates an equivalent electrical surface for CdTe/HgCdTe uniformly from the principal physical interface to the inside of the bulk material, effectively improving the characteristics of the CdTe passivation layer.
Highlights
The mercury cadmium telluride (HgCdTe) infrared (IR) photodiode is one of the most important types of advanced infrared detectors due to its performance advantage and technical maturity.1 The quality of the infrared photodiode is related to the properties of the material itself and the passivation process, especially for the long-wavelength HgCdTe infrared photodiode.2,3The lattice structure and lattice constant of CdTe are very close to those of HgCdTe; it is stable and adheres well to HgCdTe
We found that after vacuum annealing at 300 ○C for 24 h, the micromorphology of the passivation layer was significantly improved, and as the fixed charge density decreased from 1.3 × 1012 cm−2 to 1.0 × 1010 cm−2, the fast surface state density decreased from 2 × 1013 cm−2 eV−1 to 3 × 1012 cm−2 eV−1, with a minimum value of 1.2 × 1011 cm−2 eV−1
The inward passivation interface can avoid the physical defects at the CdTe growth interface and effectively improve the electrical interface characteristics of the passivation layer, which was further confirmed by the capacitance test results of the MIS devices below
Summary
The mercury cadmium telluride (HgCdTe) infrared (IR) photodiode is one of the most important types of advanced infrared detectors due to its performance advantage and technical maturity. The quality of the infrared photodiode is related to the properties of the material itself and the passivation process, especially for the long-wavelength HgCdTe infrared photodiode.. The mercury cadmium telluride (HgCdTe) infrared (IR) photodiode is one of the most important types of advanced infrared detectors due to its performance advantage and technical maturity.. The quality of the infrared photodiode is related to the properties of the material itself and the passivation process, especially for the long-wavelength HgCdTe infrared photodiode.. Scitation.org/journal/adv the HgCdTe photodiode will generate considerable surface leakage, increasing the dark current of the device and reducing the performance of the infrared detector.. According to our previous research, the series annealing experiments under different temperatures of HgCdTe covered by a CdTe layer have been implemented, and the studies have shown that the annealing process (300 ○C/24 h) can effectively improve the crystal state of the CdTe layer.. According to our previous research, the series annealing experiments under different temperatures of HgCdTe covered by a CdTe layer have been implemented, and the studies have shown that the annealing process (300 ○C/24 h) can effectively improve the crystal state of the CdTe layer. In this work, the capacitance–voltage theory of the metal–insulator–semiconductor (MIS) structure is used to analyze the changes in the electrical properties of the passivation layer introduced by the annealing process
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