Charge-Based Deep Level Transient Spectroscopy of Semiconducting and Insulating Materials
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CHARGE-BASED DEEP LEVEL TRANSIENT SPECTROSCOPY OF SEMICONDUCTING AND INSULATING MATERIALS V.I. POLYAKOV1, A.I. RUKOVISHNOKOV1, N.M. ROSSUKANYI1, B. DRUZ2 1 Institute of Radio Eng. & Electronics, RAS, 11 Mohovaya str., 103907 Moscow, Russia, E-mail: [email protected] 2 Veeco Instruments Inc., Plainview, NY 11803, USA ABSTRACT The opportunity of the charge-based deep level transient spectroscopy (Q-DLTS) for study of the structures based on wide bandgap semiconducting and insulating materials such as diamond and Al2O3 was demonstrated. Using our isothermal Q-DLTS method with rate window (τm) scanning we obtained information about concentration, activation energy and capture crosssection of the native and extrinsic electrical active defects - trapping centers (TC) in slightly boron-doped polycrystalline diamond, diamond single-crystal and in the structures Al2O3 film on NiFe and Si substrates. In comparison with widely used capacitance-based deep level transient spectroscopy, Q-DLTS gives one possibility to investigate the structures in which a capacitance does not depend on the charge state of the surface and bulk traps. INTRODUCTION Investigation of the electrically active bulk and surface defects in the structures based on wide bandgap semiconducting and insulating materials such as diamond and Al2O3 produced by different techniques is very important for understanding fundamental processes of the defect formation in these materials and structures. In most cases, defects, such as the impurity atoms, vacancies and their combination which forms complex defects, or/and extended defects generate deep levels in the forbidden band gap of materials and at the interface of the structures that behave as the trapping or recombination centers. Therefore, in order to improve the performance of the devices based on these materials and structures, detailed information about electrically active defects is needed. In this paper we report some results of charge-based deep level transient spectroscopy (QDLTS) of slightly boron-doped polycrystalline diamond films, diamond single-crystal and Al2O3 films on NiFe and Si substrates. EXPERIMENTAL DETAILS Sample preparation Polycrystalline and homoepitaxial boron-doped chemical-vapor deposition (CVD) diamond films were grown by hot-filament (HF) and microwave (MW) plasma-assisted methods, B-doped single-crystal diamonds were synthesized by high pressure high temperature (HPHT) technique, and Al2O3 films on NiFe and Si substrates were manufactured by Veeco Instrument Inc. All HF CVD boron-doped diamond films (5-10 µm thick) and MW CVD free standing diamond films with the thickness of approximately 0.4 mm were grown on Si substrates. The average size of synthetic diamond crystals was approximately of 1-2 mm, and the thickness of R3.4.1
insulating Al2O3 films was about 20 nm. A sandwich contact configuration was used for measurements of Q-DLTS spectra over the all samples. Low resistivity Ohmic contacts to diamond were prepared by a deposition of Ti/Au bilayer, and its subsequent annealing at a high
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