InN/AlN/Si (111) semiconductor-insulator-semiconductor (SIS) heterostructure for ultrafast optical fibre communication (1550 nm)

In this work, we report on InN/AlN/Si (111) SIS-based self-powered, and ultrafast photodetector, which works at an extremely important wavelength of 1550 nm (fibre communication). InN was grown on AlN/Si template by plasma-assisted molecular beam epitaxy. The heterostructure with a top-bottom (vertical) type of electrode configuration shows a responsivity of 3.36 µA/W with transit times in milliseconds range at zero bias. The variation of photocurrent with respect to power density is nonlinear with an exponent of 1.36, which might be attributed to the presence of traps at the interfaces. To further elucidate the nature of interface of the SIS heterostructure, a low-temperature vertical electrical transport behaviour was studied over a range of 100 – 400 K. It reveals that the barrier height (BH) is inhomogeneous in nature at the hetero-interface. It has been explained by assuming the presence of double Gaussian distribution of BH at the SIS interface based on thermionic emission theory.The double Gaussian distribution of the BH indicated the presence of traps at the interface which was already speculated from the photocurrent and power density relation of the photodetection studies.