Influence of Quantum-Well Number and an AlN Electron Blocking Layer on the Electroluminescence Properties of AlGaN Deep Ultraviolet Light-Emitting Diodes

Abstract

The influence of quantum-well (QW) number on electroluminescence properties was investigated and compared with that of AlN electron blocking layer (EBL) for deep ultraviolet light-emitting diodes (DUV-LEDs). By increasing the QW number, the band emission around 265 nm increased and the parasitic peak around 304 nm was suppressed. From the theoretical calculation, the electron current overflowing to the p-type layer was decreased as the QW number increased under the same injection. Correspondingly, the light output power also increased. The increment of output power from 5 QWs to 10 QWs was less than that from 10 QWs to 40 QWs, which was very different from what has been reported for blue and near-UV LEDs. The parasitic peak was still observed even when the QW number increased to 40. However, it can be suppressed efficiently by 1 nm AlN EBL for LEDs with 5 QWs. The simulation showed that the insertion of a thin EBL increased the barrier height for electron overflow and the electron current in p-type layers decreased significantly. The results contributed to the understanding of behavior of electron overflow in DUV-LEDs.

Tripling the light extraction efficiency of a deep ultraviolet LED using a nanostructured p-contact

“…This information is summarized, along with the associated complex refractive index of each material, in Table 1. We note that AlN has been used as an electron blocking layer due to improved suppression of parasitic luminescence compared to Al(Ga)N:Mg 35,36 .…”

Effect of oxygen plasma modification on Pd/Al/Au Ohmic contacts on undoped AlN

“…However, the device performance was still limited by many factors, such as the crystal quality, electrode contacts, and conductivity. In order to improve the performance of AlN based deep UVLEDs, many works have been done to improve the crystal quality [12][13][14][15][16], the p-type doping efficiency and the device structures [17][18][19][20][21][22]. It was demonstrated that the annealing process at high temperature resulted in the improvement of AlN quality [14].…”