HEMT epitaxial structure and preparation method thereof

Abstract

The invention discloses an HEMT epitaxial structure, which structurally comprises a substrate (10), a low-temperature GaN buffer layer (20), an undoped GaN high-resistance layer (30), an AlN isolation layer (40), an undoped GaN channel layer (50), a barrier layer (60) with the Al content thereof to be changing in the stepped manner, and an AlN barrier layer (70). The undoped GaN high-resistance layer and the AlN isolation layer grow after the annealing treatment of the low-temperature GaN buffer layer. Compared with the carbon-doped manner or the iron-doped manner, the crystallization quality is effectively improved and the memory effect caused by ion doping is avoided. Meanwhile, the structure is provided with multiple channels, wherein two main channels are formed at the interfaces of an AlN barrier layer and an undoped GaN channel layer with the barrier layer with the Al content thereof to be changing in the stepped manner, and multiple auxiliary channels are formed at the interface of the barrier layer with the Al content thereof to be changing in the stepped manner. Compared with a conventional HEMT device, the current driving capability of the HEMT device is enhanced. The gate leakage current of the HEMT epitaxial structure and the leakage current of the buffer layer are small, and the current driving capability is strong. Therefore, the HEMT epitaxial structure can be applied to the field of high-power electronic devices. In addition, the invention further provides a preparation method of the HEMT epitaxial structure.

Description

technical field [0001] The invention belongs to the field of power electronic device materials, and in particular relates to HEMT epitaxy technology. Background technique [0002] Currently, the main methods for growing a high-resistance buffer layer for HEMT devices include introducing C impurities and introducing Fe impurities. However, the complexity of the process is increased by doping and the crystal quality of the crystal is deteriorated; Luo W et al. [Journal of Alloys & Compounds 633 (2015): 494-498] made the resistance reach 10 by changing the annealing atmosphere 8 ohm / sq, but this value does not meet the requirements of HEMT HR-GaN. Therefore, it is necessary to explore a simpler and more effective method for growing a high-resistance buffer layer. [0003] In addition, common HEMT epitaxy is single-channel conductive, which limits the improvement of output power. Existing multi-channel HEMTs often introduce InGaN barrier layers or carry out n-type doping, etc...

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Problems solved by technology

[0003] In addition, common HEMT epitaxy is single-channel conduction, which limits the improvement of output power

Existing multi-channel HEMTs often introduce InGaN barrier layers or carry out n-type doping, etc., but the growth temperature of InGaN is much lower than that of AlGaN, and doping also increases the process complexity. Therefore, it is difficult to prepare multi-channel HEMTs by these methods Larger and difficult to independently control the conductivity of multiple channels

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