GaN vertical heterojunction field-effect transistor with charge compensation voltage-resistant structure

Abstract

The invention discloses a GaN vertical heterojunction field-effect transistor with a charge compensation voltage-resistant structure. The device is characterized in that the GaN vertical heterojunction field-effect transistor with the charge-compensation voltage-resistant structure further comprises a barrier layer, a channel layer, a current barrier layer and a charge compensation insulating layer outside an n-GaN buffer layer, and the fixed charges high in density exist at boundaries between the charge compensation insulating layer and the barrier layer, the channel layer, the current barrier layer and the n-GaN buffer layer, wherein the charge compensation insulating layer is formed by an insulating dielectric medium. The fixed charges high in density exist at boundary between the charge compensation insulating layer and the n-GaN buffer layer, so that in a voltage resistance process, negative charges at the boundary enable inversion of the closer n-GaN buffer layer, a formed p+ column consumes electrons in the n-GaN buffer layer, the buffer layer is enabled to form a p+n super junction structure which is completely exhausted, an electric field in the buffer layer is kept to 3MV / cm in the perpendicular direction after full optimization, and the a device breakdown voltage reaches a voltage-resistant limit of the GaN material.

Description

Technical field [0001] The invention relates to the field of semiconductor high withstand voltage devices, in particular to a vertical gallium nitride-based heterojunction field effect tube with a charge compensation withstand voltage structure. Background technique [0002] GaN-based heterojunction field effect transistors (GaNHeterojunctionField-EffectTransistor, GaNHFET) not only have large forbidden band width, high critical breakdown electric field, high electron saturation speed, good thermal conductivity, radiation resistance and good chemical stability, etc. At the same time, gallium nitride (GaN) material can form a two-dimensional electron gas heterojunction channel with high concentration and high mobility with materials such as aluminum gallium nitride (AlGaN), so it is especially suitable for high-voltage, high-power and high-temperature applications. It is one of the most potential transistors for power electronics applications. [0003] The existing high withstand v...

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Problems solved by technology

[0005] For the conventional GaNVHFET structure, the device mainly relies on the p-n junction formed between the p-GaN current blocking layer and the n-GaN buffer layer to withstand the withstand voltage. When the peak electric field in the device reaches the critical electric field or the leakage current reaches the threshold, the n-GaN The width of the depletion region in the buffer layer determines the breakdown voltage of the device. As the thickness of the n-GaN buffer layer increases, the width of the depletion region in the n-GaN also increases during breakdown. However, when n - When the thickness of the GaN buffer layer exceeds a certain value, the width of the depletion region in n-GaN reaches saturation during breakdown, and the breakdown voltage of the device also reaches saturation, which no longer increases with the increase of the thickness of the n-GaN buffer layer , thus limiting the high withstand voltage application of GaNVHFET

At the same time, the vertical electric field intensity in the n-GaN buffer layer will gradually decrease as it moves away from the p-n junction interface between the p-GaN current blocking layer and the n-GaN buffer layer. The integral of the vertical electric field strength along the vertical direction, the decreasing vertical electric field strength makes the breakdown voltage of the device unable to reach the GaN material limit, and cannot fully utilize the high withstand voltage advantages of GaN-based devices

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