Effects of tensile stress induced by SiO₂ passivation layer on the properties of AlGaN/GaN heterostructure photodiode

The effects of tensile stress induced by SiO₂ passivation layer on Al_xGa_1-xN/GaN heterostructure photodiode are investigated. The photodiode, with SiO₂ layer annealed at 650 °C for 30 min in O₂, shows that reverse current has decreased to 6.16 nA/cm^-2 under -10 V, two orders lower than that of the device without annealing technique. The responsivity also increases to 0.212 A/W at zero bias. The high-resolution x-ray diffraction, Hall measurements are taken to investigate the surface strain and electrical properties of p-AlGaN surface. These observations indicate that tensile stress induced by SiO₂ annealing technique can improve performances of this photodiode greatly.