Novel GaN heterojunction field effect transistor

Abstract

The invention discloses a novel GaN heterojunction field effect transistor. According to the invention, a P-type GaN buried layer is introduced into a local area of a GaN channel layer of a field effect transistor. The P-type GaN buried layer can improve the heterojunction energy band of the area so as to reduce local channel 2-DEG concentration and a pn junction field board is introduced into theGaN channel layer along the current direction so as to modulate channel electric field. According to the invention, P-type GaN buried layer and groove technology are combined together, so that a threshold value voltage regulation scheme becomes more flexible and threshold value voltage regulation of a larger range can be realized. At the same time, by the electric field modulation effect of the P-type GaN buried layer in the GaN channel layer, the maximal peak value electric field in a device can be reduced effectively and electric field distribution uniformity can be improved. Besides, the P-type GaN buried layer introduces a barrier in a GaN Buffer, so that source and drain electrode punchthrough of the device caused by Buffer electric leakage can be inhibited effectively. Therefore, compared with a traditional groove gating GaN heterojunction field effect transistor, the new structure enlarges the threshold value voltage regulation range effectively and improves the voltage resistance of the device substantially.

Description

technical field [0001] The invention belongs to the technical field of power semiconductors, and relates to a novel GaN heterojunction field effect transistor. Background technique [0002] Due to the limitations of the first two generations of semiconductor materials represented by Si and GaAs, the third generation of wide bandgap semiconductor materials has been developed rapidly because of its excellent performance. Gallium nitride (GaN) material is one of the cores of the third-generation semiconductor materials. Compared with Si, GaAs and silicon carbide (SiC), the special feature is that it has a polarization effect. Due to the polarization effect of the AlGaN / GaN heterojunction, a two-dimensional electron gas conduction channel with high concentration and high electron mobility is generated at the heterojunction interface close to the GaN side, which makes the AlGaN / GaN HEMT device have small on-resistance and fast switching speed. The characteristics of fast and hig...

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Problems solved by technology

[0005] 2. In recent years, the research work of enhanced GaN HEMT has made great progress, but the threshold voltage of enhanced GaN HEMT is relatively low (mostly less than 1V), and the performance is obviously worse than that of depletion-type HEMT.

[0007] (1) Reducing the Al composition or growing a thin barrier layer reduces the 2DEG concentration in the channel, but increases the parasitic resistance and on-state resistance of the AlGaN / GaN HEMT, so the Al composition and barrier layer thickness can only be limited reduced within the range, the threshold voltages are relatively low

[0008] (2) Growth of p-cap capping layer to achieve enhanced HEMT, but the capping layer weakens the control of the gate to the channel, reduces the transconductance of the device, which is not good for high-frequency work, and P-cap technology will introduce P-N junction When the device is working, a large number of holes will be injected into the channel, which will generate a large gate current, resulting in a series of problems such as threshold voltage hysteresis and reliability reduction.

[0009] (3) Recessed gate etching can effectively deplete the 2DEG concentration under the gate, but recessed gate etching requires precise control of the etching depth and will introduce serious etching damage

[0010] 4F-based plasma processing is a promising approach to realize enhanced HEMTs, but introduces injection damage, threshold voltage hysteresis, and high-voltage operation stability issues

However, this technology cannot completely deplete the two-dimensional electron gas in the channel, and cannot give full play to the withstand voltage advantages of GaN materials. At the same time, the deep energy level traps introduced by impurities such as carbon and iron will cause such as increased on-resistance, decreased output current, Negative effects such as current collapse effect and decreased reaction speed

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