The influence of undoped GaN surface flatness on the properties of the blue light-emitting diode wafer

Abstract

We have studied the properties of blue-LED wafers grown on GaN with similar dislocation density and different surface flatness. Results indicate that the smooth surface morphology of the undoped GaN layer leads to better layer periodicity in multiple quantum well (MQW) and smooth surface morphology of LED wafers. The surface flatness of the undoped GaN layer has little effect on the forward voltage and output power of the LED. However, the reverse leakage current and the lifetime of the LED wafer grown on the flatter GaN layer improved evidently. On the other hand, wafers grown on the GaN layer with worse surface flatness show better electrostatic discharge (ESD) characteristics.

GaP:Mg layers grown on GaN by MOCVD

“…Detailed procedure for the growth of GaN has been described elsewhere [5,13]. The sheet resistance of GaN:Mg layers was higher than 10 10 O/sq measured by the Van der Pauw Hall method using Ni/Au alloy as ohmic contacts.…”

“…However, despite the remarkable progress in device performance, there are still many problems remaining to be solved. One of the difficulties lies in the low hole concentration of the p-type layer due to the low Mg ionization percentage, which results in a highly resistive p-type GaN layer and a large metal/p-type GaN contact resistance [4][5][6]. Extensive research has been made aiming to obtain a suitable p-type layer with high hole concentration to improve the performance of GaN based devices.…”

Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching

“…The GaN epitaxial wafers used in this work were grown using metal-organic chemical vapour deposition (MOCVD) with the Thomas Swan closely-spaced showerhead reactor on (0001) sapphire substrates. [17] Trimethylgallium (TMGa), trimethylindium (TMIn), trimethylaluminum (TMAl) and ammonia (NH 3 ) were used as Ga, In, Al and N sources, respectively. The n-type doping source was silane (SiH 4 ) and the ptype doping source was cyclopentadienylmagnesium (Cp 2 Mg).…”