Study on Molecular Beam Epitaxy Grown HgCdTe Heterojunction Materials

With the development of application requirements for optoelectronic systems, infrared detectors are required to evolve toward smaller size, lighter weight, and lower power consumption, known as "SWaP³". Mercury cadmium telluride (HgCdTe) has become an important research subject for high-temperature infrared detectors due to its inherent material properties. HgCdTe heterojunction materials can reduce detector dark current and elevate the operating temperature of detectors. In situ arsenic-doped HgCdTe grown by molecular beam epitaxy (MBE) serves as the foundation for fabricating low-dark-current, high-operating-temperature detectors. This work investigates the effects of arsenic beam flux and growth temperature on arsenic doping in HgCdTe. A two-step annealing method was employed to study arsenic activation, revealing that doping concentration and annealing atmosphere significantly influence the activation rate and carrier mobility. When the doping concentration is below 5 × 10¹⁷ cm^-3, the arsenic activation rate approaches 100%. Annealing under a mixed atmosphere reduces material defects in HgCdTe and markedly improves the arsenic activation rate and carrier mobility. Si-based HgCdTe heterojunction materials were prepared using MBE, and mid-wave HgCdTe infrared detectors were fabricated based on these epitaxial materials. The test results show that the detector operating temperature is greatly increased from 77 K to 110 K, which can significantly reduce detector cost and improve reliability. The results provide significant guidance for the preparation of MBE-grown, arsenic-doped HgCdTe heterojunction materials and lay a solid foundation for the engineering of low-cost, high-operating-temperature HgCdTe infrared detectors.