High quality AlN for deep UV photodetectors

We have prepared large-area, 0.50×0.55mm2, metal-semiconductor-metal photodetectors based on AlN layers with different density of inversion domains (IDs). AlN layers were grown on (0001) sapphire substrates using gas source molecular beam epitaxy. The introduction of AlN∕GaN short period superlattices after growth of AlN nucleation layer yields significant reduction in the ID density. Photodetectors with ID density of 106cm−2 exhibit a very low dark current of 0.5fA at zero bias, which remains below 50fA up to a bias of ±30V. The peak responsivity of 0.08A∕W was obtained at a wavelength of ∼202nm.