AlGaN/GaN MIS-HEMT gate structure improvement using Al2O3 deposited by plasma-enhanced ALD

• Published in: Microelectronic engineering 2013-09, Vol.109, p.378-380
• Main Authors: Meunier, R., Torres, A., Morvan, E., Charles, M., Gaud, P., Morancho, F.
• Format: Article
• Language: English
• Subjects: AlGaN/GaN heterostructure; Aluminum gallium nitrides; Aluminum oxide; Deposition; Dispersions; Electronics; Engineering Sciences; Gallium nitrides; Gate-leakage current; Gates; Leakage current; Low frequencies; Metal insulator semiconductor high electron mobility transistor; Plama enhanced atomic layer deposition; Threshold voltage
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2013.04.020

•We increased the threshold voltage by 4V.•We reduced the gate leakage current by more than 6 orders of magnitude.•We obtained a record subthreshold slope of 80mV/dec for a drain/source bias of 5V for Id(Vg) curves.•We reduced overall trap density, thus providing very sharp and fast transitions between the on and off state.•All improvements were made in a simple way using PEALD, without any surface preparation or post-deposition treatments. In this work we evaluate the influence of the Al2O3 ALD deposition technique on AlGaN/GaN MIS-HEMT structures. It has been found that using O2 plasma as oxidizer instead of water could increase the threshold voltage considerably while greatly reducing gate leakage current. C(V) measurements have shown a very fast on/off transition even at 1kHz, with low frequency dispersion, while a record slope of 80mA/decades was achieved between the on and off states through Id(Vg) measurements. Gate leakage currents were also drastically reduced with a measured average of 1e−11A/mm for a drain–source bias of 5V.