Journal ArticleDOI
Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures: Frequency dependence of capacitance and conductance
Klaus Köhler,Wilfried Pletschen,Birte-Julia Godejohann,Stefan Müller,H. P. Menner,Oliver Ambacher +5 more
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In this article, the Debye and Drude models are used for the description of the frequency dependent admittance profiles in a range of depletion onset of the two-dimensional electron gas.Abstract:
Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures was used to determine the frequency dependent capacitance and conductance of FET devices in the frequency range from 50 Hz to 1 MHz. The nominally undoped low pressure metal-organic vapor-phase epitaxy structures were grown with an Al-content of 30%. An additional 1 nm thick AlN interlayer was placed in one structure before the Al0.3Ga0.7N layer growth. For frequencies below 108 Hz it is convenient to use equivalent circuits to represent electric or dielectric properties of a material, a method widely used, for example, in impedance spectroscopy. We want to emphasize the relation between frequency dependent admittance–voltage profiling and the corresponding equivalent circuits to the complex dielectric function. Debye and Drude models are used for the description of the frequency dependent admittance profiles in a range of depletion onset of the two-dimensional electron gas. Capacitance- and conductance-frequency profiles are fitted in the entire measured range by combining both models. Based on our results, we see contributions to the two-dimensional electron gas for our samples from surface states (80%) as well as from background doping in the Al0.3Ga0.7N barriers (20%). The specific resistance of the layers below the gate is above 105 Ω cm for both samples and increases with increasing negative bias, i.e., the layers below the gate are essentially depleted. We propose that the resistance due to free charge carriers, determined by the Drude model, is located between gate and drain and, because of the AlN interlayer, the resistance is lowered by a factor of about 30 if compared to the sample without an AlN layer.read more
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Determination of Surface Donor States Properties and Modeling of InAlN/AlN/GaN Heterostructures
Nitin Goyal,Tor A. Fjeldly +1 more
TL;DR: In this article, an analytical modeling framework is presented to describe the effects of surface donor states on the properties of bare lattice-matched InAlN/Aln/GaN heterostructures, where the distributed surface states are characterized by a donor density and a donor level that relate directly to the observable 2-D electron density and surface barrier height.
Journal ArticleDOI
Growth and Fabrication of Quasivertical Current Aperture Vertical Electron Transistor Structures
Philipp Doering,Rachid Driad,Stefano Leone,Stefan Mueller,Patrick Waltereit,Lutz Kirste,Vladimir Polyakov,Michael Mikulla,Oliver Ambacher,Oliver Ambacher +9 more
Journal Article
Electronic structure of nitride surfaces
TL;DR: In this paper, a systematic and comprehensive computational study of reconstructed GaN and InN surfaces in various orientations, including the polar c plane as well as the nonpolar a and m planes, is presented.
Journal ArticleDOI
Admittance frequency dispersion in lateral AlGaN/GaN Schottky barrier diodes: Other origins of two Gp/ω peaks
Noboru Fukuhara,Fumimasa Horikiri,Taiki Yamamoto,Takenori Osada,Kenji Kasahara,Takayuki Inoue,Takashi Egawa +6 more
TL;DR: In this paper , the authors measured capacitance C and conductance Gp/ ω-voltage V as a function of angular frequency and quantitatively determined the two ωpeak positions and intensities.
References
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The si-sio, interface – electrical properties as determined by the metal-insulator-silicon conductance technique
E. H. Nicollian,A. Goetzberger +1 more
TL;DR: In this article, a realistic characterization of the Si-SiO 2 interface is developed, where a continuum of states is found across the band gap of the silicon, and the dominant contribution in the samples measured arises from a random distribution of surface charge.
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Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistors
TL;DR: In this paper, the origin of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructure field effect transistors is examined theoretically and experimentally.
Journal ArticleDOI
Measurement of isotype heterojunction barriers by C‐V profiling
TL;DR: In this article, the conduction band discontinuity ΔEc was found to be 0.248 eV, corresponding to about to 0.66 ΔEg rather than Dingle's commonly accepted value 0.85 Δ Eg, attributed to compositional grading during LPE growth.