A Gallium Nitride-based Heterojunction Field-Effect Transistor with Composite Gate Dielectric Layer

Abstract

The invention discloses a gallium nitride-based heterojunction field effect transistor with a composite gate dielectric layer, which mainly includes a substrate, a gallium nitride buffer layer, a gallium nitride channel layer, and an aluminum gallium nitride barrier from bottom to top. layer and a composite gate dielectric layer, on the barrier layer form the source, drain and MIS structure gate in ohmic contact with it, the composite gate dielectric layer is composed of gate dielectric layers with different dielectric constants, thus in The interface of the gate dielectric layer of the channel layer forms a peak electric field, and there is a peak electron drift velocity at the peak electric field, which increases the drift velocity of electrons in the channel as a whole. At the same time, the low dielectric constant gate dielectric layer reduces the gate capacitance, making the device The frequency characteristic is improved.

Description

technical field [0001] The invention relates to the field of semiconductor devices, in particular to a gallium nitride-based heterojunction field effect transistor with a composite gate dielectric layer. Background technique [0002] Gallium nitride (GaN) based heterojunction field effect transistor has excellent characteristics such as large band gap, high critical breakdown electric field, high electron saturation velocity, good thermal conductivity, radiation resistance and good chemical stability. (GaN) materials can form two-dimensional electron gas heterojunction channels with high concentration and high mobility with materials such as aluminum gallium nitride (A1GaN), so they are especially suitable for high-voltage, high-power and high-temperature applications, and are the most suitable for power electronics applications. One of the most promising transistors. [0003] figure 1 It is a schematic diagram of a traditional GaN MIS-HFET structure based on the prior art...

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Problems solved by technology

Shortening the gate length has high requirements on the process. At the same time, with the shortening of the gate length, a serious short channel effect will occur, resulting in an increase in the subthreshold current of the device, an unsaturated output current, a decrease in the maximum DC transconductance, and a shift in the threshold voltage. Phenomena such as the decrease of the product of the frequency grid length ["Short-Channel Effect Limitations on High-Frequency Operation of AlGaN / GaN HEMTs for T-Gate Devices", IEEE Trans. Electron Devices, vol.54, no.10, pp.2589-2597 , Oct.2007.], but have adverse effects on the electrical properties of the device

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