Si窒化膜によるHgCdTeの表面保護

抄録

A SiN_x film deposited by Electron Cyclotron Resonance (ECR) Plasma CVD has been successfully used as a surface passivant for Hg_0.7Cd_0.3Te. Detailed analysis of the Te, Cd and Si at the SiN_x/HgCdTe interface using X-ray photoelectron spectroscopy indicates that the deposited SiN_x reduces the naturally grown HgCdTe native oxide. The oxygen taken from the Te and Cd oxidizes SiH₄ and produces silicon oxides which remain in the SiN_x film. The ECR-Plasma slightly damages the HgCdTe surface, but this was repaired by annealing at 100°C for 1 hour. After annealing, the SiN_x interfaces has an excellent interface with HgCdTe with surface-state density as low as 1×10¹¹cm^-2eV^-1 and a low fixed charge of -1.4×10¹¹cm^-2. Measurements of the flat-band shifts after exposure to a humid environment verified that the SiN_x is more moisture-resistant than the conventional ZnS passivant. A diode of area 4.8×10^-5cm² and λ_co of 5.4μm passivated with SiN_x had a zero-bias resistance of 4×10¹⁰Ω at 77K.