The structure and ultraviolet electroluminescence of n-ZnO-SiO_2-ZnO nanocomposite/p-GaN heterojunction LED

摘要

In the last decade, wide band-gap semiconductors (GaN, ZnO, InN, A1N, etc.) have attracted much attention because of their potential applications in the field of optoelectronic devices, such as light-emitting diodes and laser diodes. Among these wide band-gap semiconductors, the transparent conductive oxides are very attractive materials which are both electrically conductive and transparent. In particular, zinc oxide (ZnO) is a II-VI semiconductor material and has been identified as a promising material for ultraviolet (UV) photonic devices due to its direct bandgap energy of 3.37 eV at room temperature and large exciton binding energy of 60 meV, which is larger than that of GaN by about three times. ZnO also offers several advantages of the simple processing due to its compatibility with wet chemical etching, relatively low material costs, long-term stability, etc. Many techniques have been developed to grow high-quality ZnO, including molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD) (1), pulsed laser deposition (PLD) (2), filtered cathodic vacuum arc technique and atomic layer deposition (ALD).