Thermionic trap-assisted tunneling model and its application to leakage current in nitrided oxides and AlGaN∕GaN high electron mobility transistors
TL;DR: In this paper, two models of electron tunneling from metal to a semiconductor via traps are proposed, one called generalized thermionic trap-assisted tunneling (GTTT) and the other one called thermionic trapped-assisted tunnelling (TTT).
Abstract: We propose two models of electron tunneling from metal to a semiconductor via traps. In addition to the electrons below the metal Fermi level, the models also include the thermally activated electrons above the Fermi level. The first model is called generalized thermionic trap-assisted tunneling (GTTT), which considers tunneling through both triangular and trapezoidal barriers present in metal insulator semiconductor (MIS) structures. The second model is called thermionic trap-assisted tunneling (TTT), which considers tunneling through triangular barriers present in modern Schottky junctions. The GTTT model is shown to predict the low field leakage currents in MIS structures with nitrided oxide as insulator, and the TTT model is shown to predict the reverse gate leakage in AlGaN∕GaN high electron mobility transistors.
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TL;DR: In this paper, the advantages and limitations of the current-transient methods used for the study of the deep levels in GaN-based high-electron mobility transistors (HEMTs), by evaluating how the procedures adopted for measurement and data analysis can influence the results of the investigation.
Abstract: This paper critically investigates the advantages and limitations of the current-transient methods used for the study of the deep levels in GaN-based high-electron mobility transistors (HEMTs), by evaluating how the procedures adopted for measurement and data analysis can influence the results of the investigation. The article is divided in two parts within Part I. 1) We analyze how the choice of the measurement and analysis parameters (such as the voltage levels used to induce the trapping phenomena and monitor the current transients, the duration of the filling pulses, and the method used for the extrapolation of the time constants of the capture/emission processes) can influence the results of the drain current transient investigation and can provide information on the location of the trap levels responsible for current collapse. 2) We present a database of defects described in more than 60 papers on GaN technology, which can be used to extract information on the nature and origin of the trap levels responsible for current collapse in AlGaN/GaN HEMTs. Within Part II, we investigate how self-heating can modify the results of drain current transient measurements on the basis of combined experimental activity and device simulation.
320 citations
Additional excerpts
...[26], [55], [67]; or 3) deep-levels charge de-trapping by electron trap-assisted-tunneling mechanisms [14], [15], [54], [60], [70]....
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TL;DR: Stolichnov et al. as discussed by the authors showed that the voltage behavior of the leakage current has a minor dependence on thickness, which rules out the space-charge limited currents as main leakage source.
Abstract: Leakage current measurements were performed on epitaxial, single-crystal quality $\mathrm{Pb}(\mathrm{Zr},\mathrm{Ti}){\mathrm{O}}_{3}$ films with thicknesses in the $50--300\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ range. It was found that the voltage behavior of the leakage current has a minor dependence on thickness, which rules out the space-charge limited currents as main leakage source. Temperature-dependent measurements were performed to obtain more information on the transport mechanism through the metal-ferroelectric-metal (MFM) structure. The results are analyzed in the frame of interface-controlled Schottky emission. A surprisingly low value of only $0.12--0.13\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ was obtained for the potential barrier, which is much smaller than the reported value of $0.87\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ [I. Stolichnov et al., Appl. Phys. Lett. 75, 1790 (1999)]. The result is explained by the effect of the ferroelectric polarization on the potential barrier height. The low value of the effective Richardson constant, of the order of ${10}^{\ensuremath{-}7}--{10}^{\ensuremath{-}6}\phantom{\rule{0.3em}{0ex}}\mathrm{A}∕{\mathrm{cm}}^{2}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{2}$, suggests that the pure thermionic emission is not the adequate conduction mechanism for epitaxial MFM structures. The true mechanism might be interface-controlled injection, followed by a low mobility drift through the film volume.
243 citations
TL;DR: In this paper, the authors studied electron and hole injection in MoO3 charge generation layers (CGLs) commonly used for establishing balanced injection in multilayer stacked organic light-emitting diodes (SOLEDs).
Abstract: We study electron and hole injection in MoO3 charge generation layers (CGLs) commonly used for establishing balanced injection in multilayer stacked organic light-emitting diodes (SOLEDs). A compound CGL consisting of 100-A-thick MoO3 and Li-doped 4,7-diphenyl-1,10-phenanthroline in a 1:1 molar ratio is demonstrated to have a high electron generation efficiency. Charge injection from the compound CGL is modeled based on a two-step process consisting of tunneling-assisted thermionic emission over an injection barrier of (1.2±0.2) eV and a trap level due to oxygen vacancies at (0.06±0.01) eV above the MoO3 valence band edge. Peak external quantum efficiencies (EQEs) of (10.5±0.2)%, (10.1±0.2)%, (8.6±0.2)%, and (8.9±0.2)% are obtained for tris-(phenylpyridine)iridium-based electrophosphorescent OLEDs with indium tin oxide (ITO) anode/CGL cathode, CGL anode/CGL cathode, CGL anode/Al cathode, and ITO anode/Al cathode contacts, respectively. Based on our analysis, a three-element green emitting electrophosphorescent SOLED is demonstrated with a peak forward-viewing EQE=(24.3±1.0)% and a power efficiency of (19±1) lm/W.
78 citations
TL;DR: In this article, the mechanisms of the temperature-dependent forward gate current transport in the atomic-layer-deposited Al2O3/AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MISHEMT) were investigated.
Abstract: The mechanisms of the temperature-dependent forward gate current transport in the atomic-layer-deposited Al2O3/AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MISHEMT) were investigated. In contrast to the conventional Schottky-gate AlGaN/GaN HEMT, thermionic field emission was found not to be the dominant transport mechanism for the Al2O3/AlGaN/GaN MISHEMT. Fowler–Nordheim tunneling was found to be dominant at low temperature (T 0 °C).
71 citations
TL;DR: The introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM.
Abstract: The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p(+)-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I-V) curves combined with the temperature dependence of the I-V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole-Frenkel (P-F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM.
70 citations
References
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01 Jan 2000
TL;DR: In this article, a discussion of pyroelectric and piezoelectric effects in GaN-based materials and devices is presented, including the direction and magnitude of the pyrolectric field and a comparison of the piezolectric constants for GaAs-based, SiC-based and GaNbased materials.
Abstract: The GaN-based materials exhibit strong piezoelectric and pyroelectric effects. These effects are a combination of a fast response to an initial thermal flow and a slower response to heat dissipation or accumulation. This chapter deals with pyroelectric and piezoelectric effects in GaN-based materials and devices. It includes a discussion of the direction and magnitude of the piezoelectric field and a comparison of the piezoelectric constants for GaAs-based, SiC-based and GaNbased materials. The performance of GaN pyroelectric sensors is reviewed, and the piezoelectric effects in both GaN and GaN/SiC semiconductor-insulator-semiconductor structures and GaN-based superlattices are discussed.The piezoresistive effects in GaN-based devices are compared. The role of spontaneous polarization in wurtzite GaN is discussed. The GaN pyroelectric voltage coefficients are comparable to those of the pyroelectric ceramics. The GaN and related materials are well suited tbr use in pyroelectric sensing elements at elevated temperatures, above the temperature range of traditional pyroelectric materials. The piezoelectric effect can cause an electron (or hole) accumulation on the order of 1012 cm-2-1013 cm -2 in A1GaN/GaN heterostructure field effect transistors (HFET).
24 citations
TL;DR: The Schottky barrier height in Ni-low doped n -type gallium arsenide was measured in this article, and it was found that the temperature dependence of the barrier height is nearly equal to that of the energy gap in GaAs.
18 citations
TL;DR: In this article, a compact model of gate current due to Fowler-Nordheim tunneling is presented, which agrees closely with the selfconsistent numerical analyses of the surface inversion region of metaloxide-semiconductor field effect transistors (MOSFETs).
Abstract: A compact model of gate current due to Fowler–Nordheim tunneling is presented, which agrees closely with the self-consistent numerical analyses of the surface inversion region of metal–oxide–semiconductor field-effect transistors (MOSFETs). The model can quantify the measured data with the accuracy practically identical to the time consuming numerical simulation. It is also shown conclusively that image force lowering of the oxide barrier height is negligible for the oxide as thin as 1 nm. The quantum barrier lowering resulting from subband splitting is rigorously incorporated, including the effect of two-dimensional electrons inverted at the higher lying subbands. Finally, it is pointed out that the compact model can be readily generalized to include the direct tunneling in deep submicron MOSFETs.
13 citations