High-linearity AlGaN / GaN device based on ferroelectric medium

Abstract

The invention discloses a high-linearity AlGaN / GaN device based on a ferroelectric medium, a conductor layer and an AlGaN layer are arranged on a GaN layer, a barrier layer is formed, a ferroelectric film is arranged between a grid electrode and the barrier layer, and the high-linearity AlGaN / GaN device based on the ferroelectric medium is obtained. In the prior art, the linearity of a device is improved to a certain extent, but the complexity of the device is increased due to higher design requirements on a process and an epitaxial material. According to the invention, a layer of ferroelectric medium is introduced under the gate, and polarization regulation and control of the AlGaN / GaN HEMT are realized by utilizing the characteristic that the polarization intensity of the ferroelectric medium can be modulated by an external electric field and an extremely high dielectric constant, so that relatively flat transconductance is obtained. According to the high-linearity AlGaN / GaN HEMT device, the ferroelectric material is introduced and the parameters of the ferroelectric material are optimized, so that the electrical characteristics of the AlGaN / GaN HEMT device are successfully regulated and controlled, the peak transconductance is broadened, and the high-linearity AlGaN / GaN HEMT device based on the ferroelectric gate medium is realized. Therefore, an important theoretical and experimental basis is provided for further improving the performance of the device and expanding the application field.

Description

Technical Field

[0001] This invention pertains to functional devices, specifically a wide-bandgap semiconductor device, namely a high-linearity AlGaN / GaN device based on ferroelectric dielectrics, and relates to the design of a high-linearity GaN high-electron-mobility transistor under ferroelectric modulation. Background Technology

[0002] Wide bandgap semiconductor devices are a class of high-performance semiconductor devices, in which the semiconductor materials used have a wide bandgap, typically greater than 2 electron volts (eV). Research on wide bandgap semiconductor devices initially focused on wide bandgap semiconductor materials such as gallium nitride (GaN) and silicon carbide (SiC). These materials were extensively studied in the mid-20th century because of their large bandgap, enabling them to perform well in high-temperature and high-power applications.

[0003] AlGaN / GaN heterojunction high electron mobility transistors (AlGaN / GaN HEMTs), formed by combining GaN and AlGaN, are high-performance, wide-bandgap semiconductor devices, particularly suitable for radio frequency and microwave applications. These devices are widely used in wireless communications, radar systems, satellite communications, and other high-frequency, high-power applications.

[0004] However, AlGaN / GaN HEMTs face serious nonlinearity problems when used as amplifiers, that is, the device transconductance ( g m The inability to maintain a high linearity level for extended periods severely limits the application of AlGaN / GaN HEMT devices in fields such as power amplifiers. Therefore, some technical measures are needed to improve linearity.

[0005] Maintaining the flatness of the transconductance peak value is crucial for ensuring the stability and linearity of a device's performance. However, AlGaN / GaN HEMT devices face severe nonlinearity issues. Existing technologies employ gate trench technology to expand transconductance flatness, successfully fabricating dual-channel material layer structures and using trench gate etching to adjust the difference between the two channels, thereby improving the transconductance linearity of the device. Molecular beam epitaxy (MBE) is also used to fabricate thin films on the buffer layer surface, achieving quasi-self-alignment of the gate and source / drain active regions, thus improving transistor linearity. Furthermore, by periodically etching a portion of the barrier thickness in specific regions along the gate width direction, planar and trench devices are integrated in parallel along the gate width direction, significantly increasing the device's transconductance. While these methods improve device linearity to some extent, they increase device complexity due to the high requirements for process and epitaxial material design. Summary of the Invention

[0006] This invention improves the linearity of AlGaN / GaN HEMT devices by adding a ferroelectric dielectric layer between the gate and channel, thereby increasing the transconductance of the device. g m Peak broadening, g m The value can be maintained at a high level over a wide voltage range. Ferroelectric materials are a class of materials with special electrical properties; they possess the ability to change their polarization direction under the influence of an electric field. This change in polarization can be used to modulate the electrical performance of devices. The nonlinear characteristics of ferroelectric materials can be used to compensate for the nonlinearity of the device itself, thereby improving its overall linearity and broadening its range. g m Peak value.

[0007] The present invention adopts the following technical solution.

[0008] A highly linear AlGaN / GaN device based on ferroelectric dielectric includes AlGaN, GaN, source, gate, drain and barrier region, with a ferroelectric thin film disposed between the gate and the barrier layer.

[0009] In this invention, the thickness of the ferroelectric thin film is 5-100 nm; preferably, the thickness of the ferroelectric thin film is 8-80 nm; more preferably, the thickness of the ferroelectric thin film is 10-500 nm, such as 20 nm, 30 nm, 40 nm, or any thickness within the range.

[0010] In this invention, the ferroelectric thin film includes one or more of the following: lead zirconate titanate (also known as zirconium titanate, PZT) thin film, barium iron magnesium niobate (BMN) thin film, lead silicate (PbTiO3) thin film, barium titanate (BT) thin film, lead titanate (PT) thin film, barium strontium titanate (BST) thin film, and lead magnesium niobate-lead titanate (PMN-PT) thin film.

[0011] In this invention, the length of the ferroelectric thin film is the same as the gate length.

[0012] In this invention, the gate-source spacing is 1 to 7 micrometers, preferably 2 to 6 micrometers. As an example, in the high linearity AlGaN / GaN device based on ferroelectric dielectric, the gate-source spacing is any data within one or more of 2 micrometers, 2.5 micrometers, 3 micrometers, 3.5 micrometers, 4 micrometers, 4.5 micrometers, 5 micrometers, and 5.5 micrometers.

[0013] In this invention, the gate length is 0.5 to 5 micrometers, preferably 1 to 4 micrometers. As an example, in the high linearity AlGaN / GaN device based on ferroelectric dielectric, the gate length is any one or any data within the range of 1 micrometer, 1.5 micrometer, 2 micrometer, 2.5 micrometer, 3 micrometer, 3.5 micrometer, and 4 micrometer.

[0014] In this invention, the gate-drain spacing is 1 to 8 micrometers, preferably 2 to 6 micrometers. As an example, in the high linearity AlGaN / GaN device based on ferroelectric dielectric, the gate-drain spacing is any data within one or more of 2 micrometers, 2.5 micrometers, 3 micrometers, 3.5 micrometers, 4 micrometers, 4.5 micrometers, 5 micrometers, 5.5 micrometers, and 6 micrometers.

[0015] In this invention, the thickness of the barrier layer is 10-50 nm, preferably 15-40 nm, and more preferably 20-30 nm. As an example, in the high linearity AlGaN / GaN device based on ferroelectric dielectric, the thickness of the barrier layer is any data within the range of 22 nm, 25 nm, and 28 nm.

[0016] In this invention, the Al content of the barrier layer is selected from 0 to 0.5, excluding 0. Preferably, the Al content of the barrier layer is selected from 0.05 to 0.4. More preferably, the Al content of the barrier layer is selected from 0.1 to 0.35. As an example, in the high linearity AlGaN / GaN device based on ferroelectric dielectric of this invention, the Al content of the barrier layer is any data within one or more of 0.12, 0.14, 0.15, 0.16, 0.18, 0.2, and 0.3.

[0017] This invention discloses a method for fabricating the aforementioned high-linearity AlGaN / GaN device based on ferroelectric dielectric, comprising the following steps: depositing a conductor layer and an AlGaN layer on a GaN layer, forming a barrier layer, and depositing a ferroelectric thin film between the gate and the barrier layer to obtain a high-linearity AlGaN / GaN device based on ferroelectric dielectric. GaN material is obtained through MOCVD equipment or MBE growth, allowing for precise control of the surface structure, composition, and film thickness to design the device structure; using molecular beam epitaxy (MBE) to grow AlGaN material allows for control over the Al content in the final AlGaN product, which is the mass ratio of aluminum in AlGaN; and using pulsed laser deposition (PLD) to prepare the ferroelectric thin film.

[0018] This invention discloses the application of the above-mentioned highly linear AlGaN / GaN device based on ferroelectric dielectric in the fabrication of power amplifiers.

[0019] This invention discloses the application of the above-mentioned high linearity AlGaN / GaN device based on ferroelectric dielectric in improving device linearity.

[0020] In AlGaN / GaN HEMT devices, electrons primarily reside in a two-dimensional electron gas (2DEG). Adding ferroelectric materials alters the electron density distribution or mobility within the 2DEG, thereby affecting the device's performance.g m The interface between ferroelectric materials and AlGaN / GaN introduces charges, which can affect electron injection and drift, thus altering device performance. Introducing a ferroelectric thin film between the gate and channel, such as zirconium titanium leadate (PZT), barium magnesium niobate (BMN), lead silicate (PbTiO3), barium titanate (BT), lead titanate (PT), barium strontium titanate (BST), or lead magnesium niobate-lead titanate (PMN-PT), and adjusting key parameters such as the ferroelectric material's thickness, saturation polarization, remanent polarization, and coercive field, can modify material properties. This allows the ferroelectric layer to regulate the device's electrical performance, resulting in two peaks in the device's gm curve, thereby indirectly broadening the device's electrical spectrum. g m Peak performance is improved to enhance linearity. This addresses the insufficient linearity of existing AlGaN / GaN HEMT devices. g m The present invention addresses the drawback of the inability to maintain a high value for an extended period. By introducing a ferroelectric dielectric onto the gate, the electrical performance of the device can be modulated, thereby improving the electrical properties of the AlGaN / GaN HEMT device. g m曲线 Two relatively close peaks appear, thus realizing the device. g m Peak broadening improves linearity, which is particularly beneficial for high-frequency and amplification applications. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of a conventional AlGaN / GaN HEMT device structure.

[0022] Figure 2 This is the AlGaN / GaN HEMT device structure of the present invention.

[0023] Figure 3 The transfer characteristic curves before and after introducing the ferroelectric grating medium.

[0024] Figure 4 The figures show the device transfer characteristic curves, the relationship between transconductance peak value and ferroelectric layer thickness, and the relationship between ferroelectric thickness and GVS for devices with different ferroelectric dielectric thicknesses.

[0025] Figure 5 The simulation results of transconductance of the device under different Al compositions of the barrier layer are shown, as well as the extracted GVS relationship curve with Al composition.

[0026] Figure 6 The gm curves are for ferroelectric thicknesses of 50 nm, 30 nm, and 10 nm.

[0027] Figure 7The gm curves are for gates with a normal oxide layer, a ferroelectric layer, and no ferroelectric layer. Detailed Implementation

[0028] AlGaN / GaN high electron mobility transistors (HEMTs) have broad application prospects in RF and microwave power amplifiers and 5G mobile communications. Their excellent performance in high-frequency and high-power applications makes them an ideal choice for many RF and microwave electronic devices. In these applications, device linearity is particularly important, directly affecting the consistency of power gain as the gate voltage increases under large-signal operating conditions. In practical RF power amplifiers, as the input power increases, it becomes increasingly difficult for the amplifier to maintain the same amplification level, leading to a decrease in gain and thus output distortion. In microwave power applications, flat transconductance is ideal for linear operation. Existing technologies have improved device linearity to some extent, but the high requirements for process and epitaxial material design increase device complexity. This invention introduces a ferroelectric layer under the gate, utilizing its polarization intensity modulated by an applied electric field and its extremely high dielectric constant to achieve polarization control of the AlGaN / GaN HEMT, thereby obtaining a relatively flat transconductance. The influence of the introduction of ferroelectric materials on the characteristics of the device was analyzed by simulation study using Silvaco TCAD software. The main physical models used in the simulation were the SRH (Shockley-Read-Hall) composite model and the polarization model Albrct.n mobility model, in which the intensity of the polarization effect was 0.65.

[0029] The basic structure of the AlGaN / GaN HEMT device in this invention is based on existing technology, and the specific fabrication, operation and performance testing are based on conventional technology; the gate voltage swing (GVS) corresponding to 80% of the transconductance peak (gm max) is used to characterize the linearity of the transconductance (gm).

[0030] GaN and AlGaN materials are obtained through molecular beam epitaxy (MBE), which is an existing technology and allows control over the Al content in the final AlGaN product; this is a conventional technology. Ferroelectric thin films are formed using PLD, which is also a conventional technology. This does not affect the understanding of the technical effects of the present invention by those skilled in the art.

[0031] The fabrication method of highly linear AlGaN / GaN devices based on ferroelectric dielectrics is as follows: 1. Basic structure preparation: First, the basic structure of AlGaN / GaN HEMT is prepared, including the substrate, gallium nitride layer, AlGaN layer, channel layer and gate, which is a conventional technique; 2. Ferroelectric dielectric selection: Selecting ferroelectric dielectrics, such as titanium zirconium lead-acid (PZT) and barium strontium titanate (BST), primarily serves to modulate the electrical properties of AlGaN / GaN HEMTs, thereby improving device linearity and broadening the transconductance peak value. g m The value can be maintained at a high level over a wide voltage range; 3. Mask design: A mask is designed and formed using photolithography to protect a portion of the device from ion implantation. This ensures that only specific areas are implanted, which is a conventional technique. 4. Ion implantation: In the masked area, ferroelectric dielectric is implanted into the device structure using ion implantation equipment. This is a conventional technique. 5. Annealing treatment: Performing thermal annealing treatment to solidify the ferroelectric dielectric layer and promote the formation of ferroelectric domains in the crystal lattice is a conventional technique; 6. Packaging and Testing: After ion implantation and annealing, packaging and testing are performed to evaluate the performance and stability of the device, which is a standard technique.

[0032] When simulating the transfer characteristics of the device, the drain voltage VD is set to 10V, and the gate voltage VGS is scanned from -6V to 10V in steps of 0.1V. Example 1

[0033] Figure 1 This is a cross-sectional view of a conventional AlGaN / GaN HEMT device structure. The barrier layer is a planar structure located below the gate, and the gate-source spacing is L. gs , grid spacing L gd , grid length L g The AlGaN barrier layer is a conventional structure.

[0034] The AlGaN / GaN HEMT device structure of the present invention is as follows: Figure 2 As shown, the gate length is 2 micrometers, the gate-source spacing and the gate-drain spacing are both 3 micrometers, the ferroelectric layer under the gate is made of titanium zirconium lead oxide (PZT) with a dielectric constant of 50 and thicknesses of 10 nm, 20 nm, 30 nm, 40 nm and 50 nm, respectively; the GaN channel layer thickness is 400 nm, the AlGaN barrier layer thickness is 25 nm, and the Al composition is 0.16 (16 wt%).

[0035] The transfer characteristic curves before and after introducing the ferroelectric grating dielectric are as follows: Figure 3 As shown, the curves marked with squares represent conventional devices, while the curves marked with triangles represent devices that introduce ferroelectric dielectrics.

[0036] Figure 4The figures show the device transfer characteristic curves, the relationship between transconductance peak value and ferroelectric layer thickness, and the relationship between ferroelectric thickness and GVS for devices with different ferroelectric dielectric thicknesses. Example 2

[0037] According to the device structure of Example 1, the ferroelectric layer under the gate uses titanium zirconium lead oxide (PZT) with a dielectric constant of 100, and the Al composition of the AlGaN barrier layer is adjustable. Figure 5 The simulation results of transconductance of the device under different Al compositions of the barrier layer and the extracted GVS relationship curve with Al composition are shown, which shows that the ferroelectric gate dielectric significantly improves the device performance. Example 3

[0038] According to the device structure of Example 1, the ferroelectric layer under the gate uses barium strontium titanate (Ba). 0.5 Sr 0.5 TiO3), 30 nm thick, Al composition of AlGaN barrier layer 0.16; GVS 7.56.

[0039] Change barium strontium titanate (Ba 0.5 Sr 0.5 The thickness of TiO3 is 10 nm or 50 nm. Figure 6 Ferroelectric thicknesses of 50nm, 30nm, and 10nm g m curve.

[0040] Comparative Example According to the device structure of Example 1, an oxide layer with a thickness of 20 nm is set in the gate barrier layer, which is a conventional method.

[0041] Figure 7 The gate has a standard oxide layer, a ferroelectric layer, or no ferroelectric layer. g m The curve shows that significant technological progress has been made in barium strontium titanate.

[0042] This invention successfully modulates the electrical properties of AlGaN / GaN HEMT devices by introducing ferroelectric materials. Good electrical properties are achieved within constraints on the thickness of the ferroelectric material and the Al composition of the barrier layer. The introduction of ferroelectric materials allows for the appearance of a second transconductance peak, P2. By altering the relative positions of P1 and P2, the two transconductance peaks are brought closer together, thus broadening the transconductance and improving the linearity of the device. In summary, this invention successfully modulates the electrical properties of AlGaN / GaN HEMT devices by introducing ferroelectric materials and optimizing their parameters, broadening the peak transconductance and realizing a high-linearity AlGaN / GaN HEMT device based on a ferroelectric gate dielectric. This provides an important theoretical and experimental foundation for further improving device performance and expanding its application areas.

Claims

1. A highly linear AlGaN / GaN device based on ferroelectric dielectric, comprising AlGaN, GaN, source, gate, drain, and barrier region, characterized in that, A ferroelectric thin film is provided between the gate and the barrier layer.

2. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 1, characterized in that, The thickness of the ferroelectric thin film is 5–100 nm.

3. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 2, characterized in that, The thickness of the ferroelectric thin film is 8–80 nm.

4. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 1, characterized in that, Ferroelectric thin films include lead zirconate titanate thin films, barium iron magnesium niobate thin films, lead silicate thin films, barium titanate thin films, lead titanate thin films, barium strontium titanate thin films, and lead magnesium niobate-lead titanate (one or more of these thin films).

5. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 1, characterized in that, The gate-source spacing is 1–7 micrometers; the gate length is 0.5–5 micrometers; and the gate-drain spacing is 1–8 micrometers.

6. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 1, characterized in that, The thickness of the barrier layer is 10–50 nm.

7. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 1, characterized in that, The Al content of the barrier layer is selected from 0 to 0.5, excluding 0.

8. The highly linear AlGaN / GaN device based on ferroelectric dielectric according to claim 7, characterized in that, The Al content of the barrier layer is selected from 0.05 to 0.

4.

9. The method for fabricating a high linear AlGaN / GaN device based on ferroelectric dielectric as described in claim 1, comprising the following steps: depositing a conductor layer and an AlGaN layer on a GaN layer and forming a barrier layer; depositing a ferroelectric thin film between the gate and the barrier layer to obtain a high linear AlGaN / GaN device based on ferroelectric dielectric.

10. The application of the high linearity AlGaN / GaN device based on ferroelectric dielectric as described in claim 1 in the fabrication of power amplifiers; or the application of the high linearity AlGaN / GaN device based on ferroelectric dielectric as described in claim 1 in improving device linearity.

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