Application Relevant Evaluation of Trapping Effects in AlGaN/GaN HEMTs With Fe-Doped Buffer

Axelsson, Olle; Gustafsson, Sebastian; Hjelmgren, Hans; Rorsman, Niklas; Blanck, H.; Splettstoesser, Jorg; Thorpe, Jim; Roedle, Thomas; Thorsell, Mattias

doi:10.1109/ted.2015.2499313

Cited by 63 publications

(29 citation statements)

References 18 publications

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“…From Equation 26, it is obvious that C gd should be sensitive to both the voltages, ie, V ds and V gs and the effects of both can be seen independently by differentiating Equation 26 with respect to both the applied potentials, therefore,…”

Section: Ac Characteristicsmentioning

confidence: 99%

An improved temperature dependent analytical model to predict AlGaN/GaN high electron mobility transistors AC characteristics

Khan

Ahmed

Rehman

2019

Int J Numerical Modelling

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In this paper, an improved temperature dependent model has been presented to predict AC characteristics of submicron AlGaN/GaN high electron mobility transistors (HEMTs). The model evaluates effects of channel temperature on the device AC intrinsic parameters. It has been shown that the rise of channel temperature is almost linear in nature, and it depends upon both the ambient temperature as well as on the operating voltages of the device. By reassessing two dimensional electron gas (2‐DEG) carrier concentration, ns, high electron mobility transistor (HEMT)'s analytical I−V equations for both linear as well as saturation regions have been modified. The modeled DC characteristics showed a good degree of accuracy with the experimental data. By evaluating temperature and bias dependent charge accumulation in the depletion region of the device, an AC model for the device intrinsic parameters has been developed. S‐parameters of the device have been evaluated by using the modeled AC intrinsic parameters that showed a good agreement with the measured data. Thus, the developed technique could be a useful tool to predict AC parameters of submicron AlGaN/GaN HEMTs meant for harsh environments.

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Section: Ac Characteristicsmentioning

confidence: 99%

An improved temperature dependent analytical model to predict AlGaN/GaN high electron mobility transistors AC characteristics

Khan

Ahmed

Rehman

2019

Int J Numerical Modelling

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“…A defined critical concentration of Fe in the channel cannot be established, since it may depend on several factors, such as the required device characteristic and applications. Generally a 800–1000 nm thick undoped GaN layer is used in standard HEMT structure in order to prevent the above mentioned effect, but this has the drawback to increase the soft‐subthreshold behavior (also known as soft‐breakdown) and to generate dispersion effects …”

Section: Introductionmentioning

confidence: 99%

“…Generally a 800-1000 nm thick undoped GaN layer is used in standard HEMT structure in order to prevent the above mentioned effect, but this has the drawback to increase the softsubthreshold behavior (also known as soft-breakdown) and to generate dispersion effects. [24,25] Under these circumstances, it is interesting to develop an epitaxial process capable of suppressing the segregation of Fe atoms in the GaN structure, in order to grow a relatively thin undoped GaN channel layer, without Fe atoms interfering with the 2DEG. Growth parameters (temperature, pressure, V/ III ratio, growth rate, .…”

Section: Introductionmentioning

confidence: 99%

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Benkhelifa

Kirste

Manz

et al. 2017

Physica Status Solidi (b)

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AlGaN/GaN High Electron Mobility Transistors (HEMTs) require a semi‐insulating buffer to compensate a high background donor concentration and to prevent parasitic effects, such as parallel conduction. Iron and carbon are typical impurities used for such purpose, since they can behave as deep acceptors in GaN layers. The former (Fe) brings as drawback a well‐known memory effect which consists in the segregation of Fe atoms through the GaN layers, requiring thick undoped layers to keep the two‐dimensional electron gas (2DEG) away from such electron traps. The latter (C), although easier to incorporate in the GaN layers and free of any memory effect, could cause current collapse. In this study we investigate the effect of differently strained epitaxial layers on Fe‐segregation. HEMT structures were grown on sapphire substrates by MOCVD. By growing the Fe‐doped layers under unusual growth conditions (low temperature, or as AlGaN), or by adding an interlayer (AlN, 5× AlN/GaN, or C‐doped GaN) between the doped and undoped epitaxial layers, we have succeeded in limiting the Fe segregation within 200 nm of undoped GaN layer instead of the typically required 800 nm, as proven by SIMS. While the morphology and the crystal quality of the HEMT structures have been affected to a very low extent, the electrical characteristics have benefitted from such interlayers. Higher carrier mobility and lower sheet resistance distinguish such epitaxial structures. Further benefits are expected by the device performance such as reduced soft‐subthreshold behavior (soft‐breakdown) and dispersion effects.

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“…The analysis of the trapping phenomena in GaN‐based HEMTs has focused on the traps at the surface or in the AlGaN barrier layer . More recently, there has been growing interest in the use of an intentionally iron‐doped GaN buffer layer toward improving the performance of GaN‐based HEMTs . However, little attention has been given to the trapping phenomena in the unintentionally doped (UID) GaN buffer layer.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19] More recently, there has been growing interest in the use of an intentionally iron-doped GaN buffer layer toward improving the performance of GaN-based HEMTs. [20][21][22] However, little attention has been given to the trapping phenomena in the unintentionally doped (UID) GaN buffer layer. Gallium nitrides are characterized by a high density of dislocations and several undesired impurities, complexes, and point defects.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Trap Level in the Unintentionally Doped GaN Buffer Layer on Optimized p‐GaN Gate AlGaN/GaN HEMTs

Cai

Zhang³

et al. 2017

Physica Status Solidi (a)

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This research investigates the impacts of the AlGaN barrier layer thickness and the Al mole fraction on p‐GaN gate AlGaN/GaN HEMTs and presents an optimized structure. Based on 2‐D drift‐diffusion simulation, the effects of the trap level in the UID GaN buffer layer on the transfer and output characteristics of the optimized device are described. The energies of the trap levels are set at 0.28, 0.33, 0.4, 0.58, and 0.9 eV below the conduction band minimum, respectively. The depth of the trap level is found to influence the off‐state leakage current and on‐state ID,max. The Shockley–Read–Hall recombination model for a single trap level is used to analyze the impact of different trap levels in the UID GaN buffer on p‐GaN gate AlGaN/GaN HEMTs.

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Application Relevant Evaluation of Trapping Effects in AlGaN/GaN HEMTs With Fe-Doped Buffer

Cited by 63 publications

References 18 publications

An improved temperature dependent analytical model to predict AlGaN/GaN high electron mobility transistors AC characteristics

An improved temperature dependent analytical model to predict AlGaN/GaN high electron mobility transistors AC characteristics

Suppression of Iron Memory Effect in GaN Epitaxial Layers

Effects of the Trap Level in the Unintentionally Doped GaN Buffer Layer on Optimized p‐GaN Gate AlGaN/GaN HEMTs

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