Regensburg 1998 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 2: Poster I

HL 2.134: Poster

Montag, 23. März 1998, 10:30–19:00, A

Interface Defect Density in AlN-on-Si Heterostructures Determined from Capacitance Transients — •Reinhard Schwarz¹, R. Rocha¹, J. J. Sun², and P. Freitas^1,2 — ¹Physics Department, Instituto Superior Técnico, 1096 Lisboa — ²INESC, Instituto de Engenharia de Sistemas e Computadores, 1000 Lisboa, Portugal

Capacitance-voltage (C-V) and current-voltage (I-V) characteristics were employed to study the role of deep-lying traps and interface defects in MIS devices where the insulator layer is made of aluminum nitride (AlN). Thin AlN films in the thickness range netween 15 Å to 2µ m were deposited on crystalline Si and Co-coated glass substrates by reactive sputtering of Al in an Ar/N₂ plasma at room temperature. insulator films study I-V curves, measured in perpendicular direction from RT down to 20K in thin films with thicknesses below about 30 Å are well described by the tunneling model. Thicker AlN layers could be more easily fitted to a Poole-Frenkel process that is based on reemissionof deeply trapped carriers. A confirmation of the hypotheses of defect related transport through the AlN films comes from sweep-out experiments in the MIS structures. In this technique defects are charged (discharged) by applying short voltage pulses. From the observed shift of the C-V curves and from the current transients we estimated an interface defect density of about 10¹² cm⁻²eV⁻¹ at an energy depth of 0.7 eV below the transport path.