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Polarization Induced Effects in AlGaN/GaN Heterostructures

100%

Ambacher O.

Acta Physica Polonica A

2000

vol. 98

issue 3

195-201

Two-dimensional hole and electron gases in wurtzite GaN/Al_{x}Ga_{1-x}N/GaN heterostructures areinduced by strong polarization induced effects. The sheet carrier concentration and the confinement of the two-dimensional carrier gases located close to one of the AlGaN/GaN interfaces are sensitive to a high number of different physical properties such as polarity, alloy composition, strain, thickness, and doping. We have investigated the structural quality, the carrier concentration profiles, and electrical transport properties by a combination of high resolution X-ray diffraction, Hall effect, and C-V profiling measurements. The investigated heterostructures with N- and Ga-face polarity were grown by metalorganic vapor phase or plasma induced molecular beam epitaxy covering a broad range of alloy compositions and barrier thickness. By comparison of theoretical and experimental results we demonstrate that the formation of two-dimensional hole and electron gases in GaN/AlGaN/GaN heterostructures both rely on the difference of the polarization between the AlGaN and the GaN layer. In addition the role of polarity on the carrier accumulation at different interfaces in n- and p-doped heterostructures will be discussed in detail.

Electroluminescence Investigation of the Lateral Field Distribution in AlGaN/GaN HEMTs for Power Applications

27%

Baeumler M., Polyakov V., Gütle F., Dammann M., Benkhelifa F., Waltereit P., Reiner R., Müller S., Wespel M., Quay R., Mikulla M., Wagner J., Ambacher O.

vol. 125

issue 4

982-985

The lifetime and stability of AlGaN/GaN heterostructure field effect transistors at high power levels can be enhanced by introducing field plates to reduce electric field peaks in the gate-drain region. Simulations of the electric field distribution along the channel using the 2D ATLAS software from Silvaco indicate that above a characteristic drain source voltage three spatially separated electric field peaks appear, one located at the drain-side edge of the gate foot, one at the end of the drain-sided gate field plate, and one at the end of the source shield field plate. The close correlation between lateral electric field and the electroluminescence due to hot electron related intra-band transitions can be very helpful when optimizing the electric field distribution in high power devices. Electroluminescence microscopy images of devices with gate and source shield field plate reveal the peaks located at the locations of enhanced electric field. By studying the voltage dependence of the electroluminescence peaks the influence of the field plates on the electric field distribution in source drain direction can be visualized.

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2 Acta Physica Polonica A

1 2014

1 2000

2 Ambacher O.

1 Baeumler M.

1 Benkhelifa F.

1 Dammann M.

1 Gütle F.

1 Mikulla M.

1 Müller S.

1 Polyakov V.

1 Quay R.

1 Reiner R.

1 Wagner J.

1 Waltereit P.

1 Wespel M.

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Polarization Induced Effects in AlGaN/GaN Heterostructures

Electroluminescence Investigation of the Lateral Field Distribution in AlGaN/GaN HEMTs for Power Applications