Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 73: GaN: Preparation and Characterization IV

HL 73.3: Talk

Thursday, March 29, 2012, 10:00–10:15, ER 270

Electrical properties of p-type AlGaN/GaN layers on Si substrates — Antje Rohrbeck, •Hartmut Witte, Phannee Sangkaew, Peter Veit, Bernd Garke, Armin Dadgar, Juergen Christen, Ruediger Goldhahn, and Alois Krost — Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany

AlGaN/AlN layers on Si-substrates are the base of new UV- LEDs with additional applications in sensoring and information storage. Effective p-type doping of AlGaN is hindered by the increase of the Mg acceptor activation energy with increasing Al content and by an increased defect density using Si substrates. For an enhancement of the hole concentration in p-AlGaN layers a p-type AlGaN:Mg/GaN:Mg superlattice(SL) was grown. The doping properties of this SL were compared with single p-type GaN and p-type AlGaN (x=0.1) layers characterized by CV- and impedance spectroscopy and scanning capacitance microscopy. Furthermore, the impact of the density and the character of structural defects of the surface properties were characterized by atomic force microscopy and scanning surface potential microscopy in correlation with transmission electron microscopy. To investigate electrical surface properties X-ray photoemission spectroscopy and the serial resistance of a lateral Schottky junction were applied. Inversion domains and dislocations were observed in the p-GaN and p-AlGaN layers increasing the serial resistances of the Schottky contacts and reducing the forward current densities. In contrast, the AlGaN/GaN SL surface shows only marginal surface defects.