Ultraviolet-enhanced light emitting diode employing individual ZnO microwire with SiO2 barrier layers

Abstract

This paper details the fabrication of n-ZnO single microwire (SMW)-based high-purity ultraviolet light-emitting diodes (UV-LEDs) with an added SiO2 barrier layer on the p-Si substrate. However, the current-voltage (I-V) curve exhibited non-ideal rectifying characteristics. Under forward bias, both UV and visible emissions could be detected by electroluminescence (EL) measurement. When bias voltage reached 60 V at room temperature, a UV emission spike occurred at 390 nm originating from the n-ZnO SMW. Compared with the EL spectrum of the n-ZnO SMW/p-Si heterojunction device without the SiO2 barrier layer, we saw improved UV light extraction efficiency from the current-blocking effect of the SiO2 layer. The intense UV emission in the n-ZnO SMW/SiO2/p-Si heterojunction indicated that the SiO2 barrier layer can restrict the movement of electrons as expected and result in effective electron-hole recombination in ZnO SMW.