Ammono S.A. in Warsaw, Poland, which produces bulk gallium nitride (GaN) using ammonothermal technology, has added a new product in its portfolio – the p-type truly bulk AMMONO-GaN substrate – to be presented by Dr Marcin Zajac on 25 August (Growth 1 session at 15:45pm) at the International Workshop on Nitride Semiconductors (IWN2014), which takes place in Wroclaw, Poland (24–29 August).
Typically, dedicated donor doping can increase GaN conductivity, providing electrons as majority charge carriers (n-type). Successful and efficient p-type doping of GaN has always been a difficult technological task, because of the high activation energy of typical acceptors. Until now, only thin layers of p-type GaN could be obtained by epitaxial methods or ion implantation.
In contrast, in the ammonothermal process the incorporation of acceptors during growth results in a larger hole concentration and p-type conductivity, without the generation of structural defects. The dislocation density in p-type AMMONO-GaN remains the same as the dislocation density of n-type AMMONO-GaN substrates, being below 5x104cm-2. Carrier (free hole) concentration in this material is at the level of 1016cm-3, while electrical resistivity is 10-100Ω.cm.
Ammono says that the new p-type GaN substrates should enable the fabrication of novel devices. In this area, where many solutions are already patented, the introduction of such a new substrate offers new potential for device architectures, reckons the firm. It is expected that laser diodes, LEDs, high-power transistors and high-frequency transistors may gain many benefits by using this new material.
