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Hot electron induced non-saturation current behavior at high electric field in InAlN/GaN heterostructures with ultrathin barrier

View Article: PubMed Central - PubMed

ABSTRACT

The high-field transport characteristics of nearly lattice-matched InAlN/GaN heterostructures with different barrier thickness were investigated. It is found that the current in the InAlN/GaN heterostructures with ultrathin barrier shows unsaturated behaviors (or secondary rising) at high voltage, which is different from that of AlGaN/GaN heterostructures. This phenomenon is more obvious if the barrier thickness is thinner and the channel width is narrower. The experimental results demonstrate that it is the increasing carrier density excited from the more defect states by the hot electrons with larger electron saturation velocity that results in the unsaturated current behaviors in InAlN/GaN heterostructures. Our results pave a way for further optimizing InAlN barrier design and improving the reliability of InAlN/GaN HEMTs.

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Temperature-dependence carrier density of the AlGaN/GaN heterostructure and InAlN/GaN heterostructure with 4 nm-InAlN barrier.
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f4: Temperature-dependence carrier density of the AlGaN/GaN heterostructure and InAlN/GaN heterostructure with 4 nm-InAlN barrier.

Mentions: The temperature-dependence of the 2DEG sheet density of the InAlN/GaN heterostructure (4 nm-barrier) and AlGaN/GaN heterostructure are shown in Fig. 4. In the temperature range of 100–700 K, the carrier density of AlGaN/GaN has a weak dependence on temperature, showing a typical 2DEG behavior. However, the temperature-dependence of the density in the InAlN/GaN heterostructure shows a standard shallow-donor behavior. The activation energy of the donor is around 90 meV from the fitting result using a donor model. Since the GaN buffer is the same between the AlGaN/GaN and InAlN/GaN heterostructure, the donor may exist in the InAlN layer or interface. It should be mentioned that there are also other defect states with deeper level existing in the InAlN layer or interface, as revealed by capacitance-voltage and deep-level transient spectroscopy experiments8212223. The donor defect with an activation energy of 90 meV exhibited by the temperature-dependence Hall measurement is just the most easily excited by the high temperature and contributes to the sheet density. In fact, the hot electron temperature in the InAlN/GaN heterostructure may be much higher than the upper limitation of the temperature range in our Hall testing system. Therefore, it is reasonable to deduce that the hot electrons can also easily excite the electrons trapped in the deeper defects states in the InAlN/GaN heterostructure, which may also contributes to the secondary rising behaviors.


Hot electron induced non-saturation current behavior at high electric field in InAlN/GaN heterostructures with ultrathin barrier
Temperature-dependence carrier density of the AlGaN/GaN heterostructure and InAlN/GaN heterostructure with 4 nm-InAlN barrier.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120260&req=5

f4: Temperature-dependence carrier density of the AlGaN/GaN heterostructure and InAlN/GaN heterostructure with 4 nm-InAlN barrier.
Mentions: The temperature-dependence of the 2DEG sheet density of the InAlN/GaN heterostructure (4 nm-barrier) and AlGaN/GaN heterostructure are shown in Fig. 4. In the temperature range of 100–700 K, the carrier density of AlGaN/GaN has a weak dependence on temperature, showing a typical 2DEG behavior. However, the temperature-dependence of the density in the InAlN/GaN heterostructure shows a standard shallow-donor behavior. The activation energy of the donor is around 90 meV from the fitting result using a donor model. Since the GaN buffer is the same between the AlGaN/GaN and InAlN/GaN heterostructure, the donor may exist in the InAlN layer or interface. It should be mentioned that there are also other defect states with deeper level existing in the InAlN layer or interface, as revealed by capacitance-voltage and deep-level transient spectroscopy experiments8212223. The donor defect with an activation energy of 90 meV exhibited by the temperature-dependence Hall measurement is just the most easily excited by the high temperature and contributes to the sheet density. In fact, the hot electron temperature in the InAlN/GaN heterostructure may be much higher than the upper limitation of the temperature range in our Hall testing system. Therefore, it is reasonable to deduce that the hot electrons can also easily excite the electrons trapped in the deeper defects states in the InAlN/GaN heterostructure, which may also contributes to the secondary rising behaviors.

View Article: PubMed Central - PubMed

ABSTRACT

The high-field transport characteristics of nearly lattice-matched InAlN/GaN heterostructures with different barrier thickness were investigated. It is found that the current in the InAlN/GaN heterostructures with ultrathin barrier shows unsaturated behaviors (or secondary rising) at high voltage, which is different from that of AlGaN/GaN heterostructures. This phenomenon is more obvious if the barrier thickness is thinner and the channel width is narrower. The experimental results demonstrate that it is the increasing carrier density excited from the more defect states by the hot electrons with larger electron saturation velocity that results in the unsaturated current behaviors in InAlN/GaN heterostructures. Our results pave a way for further optimizing InAlN barrier design and improving the reliability of InAlN/GaN HEMTs.

No MeSH data available.