Dresden 2014 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Nitrides: Devices

HL 19.8: Talk

Monday, March 31, 2014, 16:45–17:00, POT 151

Defect characterisation in AlInN/AlN/GaN HEMT structures on Si(111) — •Aqdas Fariza, Hartmut Witte, Jonas Hennig, Oliver Krumm, Jürgen Bläsing, Armin Dadgar und Alois Krost — Institute of Experimental Physics, Otto-von-Guericke-University-Magdeburg, Magdeburg, Germany

AlGaN/GaN based high electron mobility transistors (HEMTs) are well established for many applications and can be improved in carrier density by using AlInN instead of AlGaN. Growing such structures on Si is advantageous due to lower substrate cost and large substrate diameter, as well as simpler processing. But, due to unavoidable traps performance problems occur. They mostly lead to leakage currents but also other limitation in device parameters. Therefore, investigations of these traps are essential to optimize HEMT devices. We have grown capped AlInN/AlN/GaN HEMTs on Si(111) by MOVPE with nearly lattice matched In-content. Samples were prepared with a Ni/Au-Schottky like contact and an annealed Ohmic contact deposited on top of the layers. I-V- and C-V-characteristics were carried out in dependence of frequencies and temperatures. Simultaneously, we measured the frequency and temperature dependent capacitances and conductance. These investigations exhibit several strong interface defect states located between the metal contact and the GaN buffer layer. Based on a complex equivalent circuit we were able to localize two interface defect states. We will also show significant differences in the interface defect densities between the investigated samples.