Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 73: GaN: Preparation and Characterization IV

HL 73.1: Talk

Thursday, March 29, 2012, 09:30–09:45, ER 270

AlInN/GaN-heterostructures for sensing applications — •Malte Fandrich, Timo Aschenbrenner, Stephan Figge, Thorsten Mehrtens, Andreas Rosenauer, and Detlef Hommel — Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee NW1, 28359 Bremen, Germany

Commonly, Al_0.28Ga_0.72N-based heterostructures are applied as open-gate sensors utilizing the 2-dimensional electron gas (2DEG), which originates from the polarization discontinuity between GaN and a thin AlGaN top layer. Since Al_0.82In_0.18N exhibits a higher polarization difference and is lattice matched to GaN, AlInN is a promising candidate to replace conventionally used AlGaN and to improve the sensor characteristics.
Both, strained AlGaN and lattice matched AlInN layers were grown by MOVPE on GaN buffer layers using c-plane sapphire substrates. All epitaxial structures were charaterized by HRXRD, SEM, AFM and TEM, particularly with respect to strain, defect density, as well as surface and interface roughness of the structures. In addition, sheet carrier density and mobility of the 2DEG were determined by Hall-measurements. The influence of the growth parameters on the structural quality of AlInN and its impact on the electrical properties will be discussed. Based on the heterostructures open-gate sensors were processed and their sensing behavior regarding polar liquids and gases were investigated. A comparison of the device performances proves the superior capability of AlInN/GaN-heterostructures for sensing applications.