Gallium nitride radical heterojunction field effect transistor structure and method for making the same

Abstract

The invention is a GaN-based HFET structure, which comprises an underlay, a low-temperature GaN nucleating layer which is set on the underlay; a resistive formation doped or unintended doped with GaN, which is made on the upside of the low-temperature GaN nucleating layer; an unintended doped high mobility GaN layer, which is set on the upside of the resistive formation unintended doped with GaN; an aluminum nitride interposed layer, which is made on the unintended doped high mobility GaN layer; a component step change AlxInyGazN layer unintended doped or doped in type N, which is set on the aluminum nitride interposed layer.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, in particular to a GaN-based heterojunction field-effect transistor structure and a manufacturing method using a composition-graded barrier layer and a high-mobility GaN channel layer, which can significantly reduce the The lattice defect of the material, improving the surface morphology of the material and increasing the two-dimensional electron gas mobility of the channel. Background technique [0002] As a typical representative of the third-generation wide-bandgap semiconductor, gallium nitride has excellent thermal and chemical stability, high breakdown voltage, high electron saturation drift velocity and excellent radiation resistance, and is especially suitable for the preparation of high temperature, high Heterojunction field effect transistors with high frequency, high power and radiation resistance. Gallium nitride-based heterojunction field effect transistors have broad applica...

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Problems solved by technology

However, doping will reduce the integrity of the material lattice, resulting in a decrease in the crystal quality of the AlGaN layer, and an increase in the roughness of the interface between the GaN and AlGaN layers, so the effect of improving the mobility is not ideal; (2) Using a high Al composition barrier layer AlGaN / GaN HEMT structure, as the Al composition of the barrier layer increases, the heterojunction band order and polarization electric field increase, which can significantly increase the two-dimensional electron gas concentration

However, when the Al composition is high, the large lattice mismatch will lead to the deterioration of the crystal quality, surface and interface quality of the AlGaN barrier layer, and the strain-induced deep level defects will increase, which will enhance the scattering and reduce the mobility; At the same time, when the Al composition is too high, the large lattice mismatch limits the thickness of the barrier layer, making it difficult to generate a strong two-dimensional electron gas

The two methods commonly used at present are effective in increasing the concentration of two-dimensional electron gas, but the effect is not particularly satisfactory in improving the mobility of two-dimensional electron gas. Other methods need to be further adopted to improve the field effect of gallium nitride-based heterojunctions. Two-dimensional Electron Gas Mobility of Transistor Structure Materials

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