Description:BACKGROUND
Field of Invention
[001] Embodiments of the present invention generally relate to a transistor and particularly to a high-electron-mobility transistor (HEMT).
Description of Related Art
[002] Radio-frequency (RF) power amplification has seen continuous advancements to meet the increasing demands of modern communication, satellite, and radar systems. RF power amplifiers are integral to these applications, requiring precise engineering to handle high power levels and operate efficiently across various frequency ranges. Over time, different semiconductor technologies have been explored to develop transistors capable of sustaining high-frequency operation while addressing issues related to power handling, signal integrity, and thermal performance.
[003] Further, a transition from conventional semiconductor materials to alternative wide-bandgap materials has led to extensive research into device architectures that can meet the stringent requirements of RF applications. Various approaches have been investigated to refine transistor structures, focusing on aspects such as carrier transport, leakage suppression, and thermal stability. Developments in semiconductor fabrication processes and material integration techniques have also been explored to enhance device characteristics under high-power and high-frequency operating conditions.
[004] Despite these efforts, certain constraints persist, influencing factors such as current stability, breakdown mechanisms, and signal distortion under operational stress. These factors necessitate further exploration of device design and material engineering strategies to address the evolving challenges in RF power amplification. As the demand for higher power densities and frequency performance continues to rise, ongoing research aims to develop new transistor architectures that can adapt to the needs of next-generation communication and radar technologies.
[005] There is thus a need for an improved and advanced high-electron-mobility transistor (HEMT) that can administer the aforementioned limitations in a more efficient manner.
SUMMARY
[006] Embodiments in accordance with the present invention provide a high-electron-mobility transistor (HEMT). The transistor comprising a double-channel heterostructure stack. The double-channel heterostructure stack is selected from an Aluminum Nitride (AlN), a Gallium Nitride (GaN), an Aluminum Gallium Nitride (AlGaN), or a combination thereof. The transistor further comprising a p-doped Gallium Nitride (GaN) gate adapted to induce normally-off operation by creating a depletion region at the double-channel heterostructure stack. The transistor further comprising a back-barrier adapted for improved electron confinement in the double-channel heterostructure stack. The transistor further comprising a two-dimensional electron gas (2DEG) layer adapted to be formed at a heterojunction interface of the double-channel heterostructure stack to facilitate high carrier mobility and efficient current flow in the transistor.
[007] Embodiments in accordance with the present invention further provide a method for fabrication of a high-electron-mobility transistor (HEMT). The method comprising steps of depositing a double-channel heterostructure stack on a substrate to form a two-dimensional electron gas (2DEG) layer at a heterojunction interface; forming a p-doped Gallium Nitride (GaN) gate over the heterostructure to create a depletion region at a gate-channel interface for normally-off operation; incorporating a back-barrier beneath the heterostructure to confine electrons and reduce leakage current; etching the p-doped Gallium Nitride (GaN) gate to define a gate structure; depositing and patterning source and drain electrodes to make ohmic contacts with the two-dimensional electron gas (2DEG) layer; applying passivation layers to enhance the transistor and protect against environmental effects; and optimizing the transistor to enhance carrier confinement, reduce gate leakage, and improve overall performance.
[008] Embodiments of the present invention may provide a number of advantages depending on their particular configuration. First, embodiments of the present application may provide a high-electron-mobility transistor (HEMT).
[009] Next, embodiments of the present application may provide a high-electron-mobility transistor (HEMT) that ensures superior confinement of the two-dimensional electron gas (2DEG), leading to higher electron mobility and improved RF performance.
[0010] Next, embodiments of the present application may provide a high-electron-mobility transistor (HEMT) that significantly minimizes gate leakage, improving device reliability and efficiency compared to conventional Schottky-gate GaN HEMTs.
[0011] Next, embodiments of the present application may provide a high-electron-mobility transistor (HEMT) that increases carrier density, enabling higher saturation current and superior power amplification capabilities, making it ideal for high-frequency applications.
[0012] Next, embodiments of the present application may provide a high-electron-mobility transistor (HEMT) that enhances signal linearity, reducing distortion in RF power amplifiers and boosting overall efficiency.
[0013] Next, embodiments of the present application may provide a high-electron-mobility transistor (HEMT) that minimizes strain-induced polarization effects, leading to stable operation at high frequencies and under high power loads.
[0014] These and other advantages will be apparent from the present application of the embodiments described herein.
[0015] The preceding is a simplified summary to provide an understanding of some embodiments of the present invention. This summary is neither an extensive nor exhaustive overview of the present invention and its various embodiments. The summary presents selected concepts of the embodiments of the present invention in a simplified form as an introduction to the more detailed description presented below. As will be appreciated, other embodiments of the present invention are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and still further features and advantages of embodiments of the present invention will become apparent upon consideration of the following detailed description of embodiments thereof, especially when taken in conjunction with the accompanying drawings, and wherein:
[0017] FIG. 1A illustrates a schematic block diagram of a high-electron-mobility transistor (HEMT), according to an embodiment of the present invention;
[0018] FIG. 1B illustrates a cross section view of the high-electron-mobility transistor (HEMT), according to an embodiment of the present invention; and
[0019] FIG. 2 depicts a flowchart of a method for fabrication of a high-electron-mobility transistor (HEMT), according to an embodiment of the present invention.
[0020] The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including but not limited to. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements common to the figures. Optional portions of the figures may be illustrated using dashed or dotted lines, unless the context of usage indicates otherwise.
DETAILED DESCRIPTION
[0021] The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the scope of the invention as defined in the claims.
[0022] In any embodiment described herein, the open-ended terms "comprising", "comprises”, and the like (which are synonymous with "including", "having” and "characterized by") may be replaced by the respective partially closed phrases "consisting essentially of", “consists essentially of", and the like or the respective closed phrases "consisting of", "consists of”, the like.
[0023] As used herein, the singular forms “a”, “an”, and “the” designate both the singular and the plural, unless expressly stated to designate the singular only.
[0024] FIG. 1A illustrates a schematic block diagram of a high-electron-mobility transistor (HEMT) 100 (hereinafter referred to as a transistor 100), according to an embodiment of the present invention. The transistor 100 may be designed to suitable for applications such as high-frequency power amplification and/or millimeter-wave communication systems.
[0025] According to an embodiment of the present invention, the transistor 100 may be fabricated using a Complementary Metal-Oxide-Semiconductor (CMOS)-compatible process. The CMOS-compatible process may enable seamless integration with existing semiconductor manufacturing technologies for mass fabrication of the transistor 100 with high yield.
[0026] The transistor 100 may feature a heterostructure and a barrier structure. The heterostructure and the barrier structure may be grown using a Metal Organic Chemical Vapor Deposition (MOCVD). Further, a device mesa isolation in the transistor 100 may be achieved using a process of dry etching with an Inductively Coupled Plasma (ICE) and a Reactive-Ion Etching (RIE). Further, a Source (S) and a Drain (D) ohmic contacts may be formed on the transistor 100 using a process of e-beam evaporation. According to an embodiment of the present invention, the dry etching process may achieve a depth resolution of less than 5 Nanometers (nm), for precise fabrication of the transistor 100.
[0027] Additionally, a rapid thermal annealing in nitrogen gas may be carried out to ensure rigidity in the Source(S) and the Drain (D) ohmic contacts formation. Finally, a passivation layer may be deposited on the transistor 100 using a Plasma-Enhanced Chemical Vapor Deposition (PECVD). The passivation layer may be deposited after defining a gate using an E-beam lithography process.
[0028] According to the embodiments of the present invention, the transistor 100 may incorporate non-limiting hardware components to enhance the processing speed and efficiency such as the transistor 100 may comprise a double-channel heterostructure stack 102, a p-doped Gallium Nitride (GaN) gate 104, a back-barrier 106, and a two-dimensional electron gas (2DEG) layer 108. In an embodiment of the present invention, the hardware components of the transistor 100 may be integrated with computer-executable instructions for overcoming the challenges and the limitations of the existing transistors. Further, the components may be configured to enable a higher breakdown voltage and improved thermal management for making the transistor 100 suitable for high-power and high-frequency applications.In an embodiment of the present invention, the double-channel heterostructure stack 102 may be a primary building block of the transistor 100.
[0029] According to the embodiments of the present invention, the double-channel heterostructure stack 102 may be adapted to enhance carrier density resulting in higher saturation current and improved performance at high frequencies. The double-channel heterostructure stack 102 may be, but not limited to, an Aluminum Nitride (AlN), a Gallium Nitride (GaN), an Aluminum Gallium Nitride (AlGaN), and so forth. Embodiments of the present invention are intended to include or otherwise cover any double-channel heterostructure stack 102, including known, related art, and/or later developed technologies. The double-channel heterostructure stack 102 may provide a high breakdown voltage of over 800 Voltes (V) to be suitable for high-power applications. The double-channel heterostructure stack 102 may further support a cut-off frequency (fₜ) of up to 150 GHz and a maximum oscillation frequency (fmax) exceeding 250 GHz, making it ideal for RF and millimeter-wave applications. The incorporation of AlGaN with a composition of ~25% Al achieves optimal bandgap engineering, reducing parasitic leakage while maintaining high carrier velocity.
[0030] In an embodiment of the present invention, the p-doped Gallium Nitride (GaN) gate 104 may be adapted to induce normally-off operation by creating a depletion region at the double-channel heterostructure stack 102. The p-doped Gallium Nitride (GaN) gate 104 may be adapted to effectively modulate the two-dimensional electron gas (2DEG) layer 108 and reduce gate leakage current, leading to enhanced threshold voltage control. Further, an integration of the double-channel heterostructure stack 102 and the p-doped Gallium Nitride (GaN) gate 104 ensures low on-resistance and high drain current, making the transistor 100 suitable for power amplification applications.
[0031] In an embodiment of the present invention, the back-barrier 106 may be adapted for improved electron confinement in the double-channel heterostructure stack 102. The back-barrier 106 may be adapted to reduce leakage in the double-channel heterostructure stack 102. The back-barrier 106 may be adapted to enhance polarization effects to increase a density of the two-dimensional electron gas (2DEG) layer 108 leading to improvement in electron mobility. The back-barrier 106 may be adapted to improve current drive efficiency by confining electrons in a lower channel and reducing leakage to a buffer layer. Further, an integration of the double-channel heterostructure stack 102 and the back-barrier 106 may enhance thermal stability for reliable operation of the transistor 100 at high power levels. The back-barrier 106 may be fabricated using materials such as, but not limited to, an Indium Gallium Nitride (InGaN), an Aluminum Gallium Nitride (InGaN), and so forth. Embodiments of the present invention are intended to include or otherwise cover any material for fabrication of the back-barrier, including known, related art, and/or later developed technologies.
[0032] In a preferred embodiment of the present invention, the back-barrier 106 may be composed of Indium Gallium Nitride (InGaN) for effectively increasing 2DEG confinement and achieving electron mobility exceeding 2200 cm²/Vs. This structure may result in reduced buffer leakage currents, typically below 10⁻⁸ A/mm², even at high drain biases. The use of back-barriers also significantly enhances device thermal stability, maintaining stable operation up to 300°C.
[0033] In an embodiment of the present invention, the two-dimensional electron gas (2DEG) layer 108 may be adapted to be formed at a heterojunction interface of the double-channel heterostructure stack 102. The two-dimensional electron gas (2DEG) layer 108 may facilitate high carrier mobility and efficient current flow in the transistor 100.
[0034] FIG. 1B illustrates a cross-section view of the transistor 100, according to an embodiment of the present invention. The transistor 100 may be fabricated using the Complementary Metal-Oxide-Semiconductor (CMOS)-compatible process. The transistor 100 may feature the double-channel heterostructure stack 102 and the back-barrier 106. The double-channel heterostructure stack 102 and the back-barrier 106 may be grown using the Metal Organic Chemical Vapor Deposition (MOCVD). Further, the device mesa isolation in the transistor 100 may be achieved using a process of dry etching with an Inductively Coupled Plasma (ICE) and a Reactive-Ion Etching (RIE). Further, the contacts (not shown) may be formed on the transistor 100 using a process of e-beam evaporation. Additionally, a rapid thermal annealing in nitrogen gas may be carried out to ensure rigidity in the ohmic contacts contact formation. Further, the passivation layer (not shown) may be deposited on the transistor 100 using a Plasma-Enhanced Chemical Vapor Deposition (PECVD). The passivation layer may be deposited after defining the p-doped Gallium Nitride (GaN) gate 104 using an E-beam lithography process.
[0035] FIG. 2 depicts a flowchart of a method 200 for the fabrication of the transistor 100, according to an embodiment of the present invention.
[0036] At step 202, a specification of the double-channel heterostructure stack 102, the p-doped Gallium Nitride (GaN) gate 104, the back-barrier 106, and the two-dimensional electron gas (2DEG) layer 108 may be conceptualized.
[0037] At step 204, the double-channel heterostructure stack 102, the p-doped Gallium Nitride (GaN) gate 104, the back-barrier 106, and the two-dimensional electron gas (2DEG) layer 108 may be fabricated on a substrate.
[0038] At step 206, the fabricated substrate may undergo a Direct Current (DC)-Radio Frequency (FR) sputtering test.
[0039] At step 208, the specification of the double-channel heterostructure stack 102, the p-doped Gallium Nitride (GaN) gate 104, the back-barrier 106, and the two-dimensional electron gas (2DEG) layer 108 may be verified. If the specification of the double-channel heterostructure stack 102, the p-doped Gallium Nitride (GaN) gate 104, the back-barrier 106, and the two-dimensional electron gas (2DEG) layer 108 may be amended, then the method 200 may proceed to a step 210. Else, the method 200 may proceed to a step 212.
[0040] At step 210, the specification of the double-channel heterostructure stack 102, the p-doped Gallium Nitride (GaN) gate 104, the back-barrier 106, and the two-dimensional electron gas (2DEG) layer 108 may be amended.
[0041] At step 212, the transistor 100 may be designed using the conceptualized specification of the double-channel heterostructure stack 102, the p-doped Gallium Nitride (GaN) gate 104, the back-barrier 106, and the two-dimensional electron gas (2DEG) layer 108.
[0042] At step 214, the transistor 100 may be fabricated. This step may include various microfabrication techniques such as photolithography, etching, metallization, and annealing to form the active regions of the transistor 100 including gate contacts, and/or interconnects. The fabrication process may ensure proper alignment of layers, minimal defects, and high yield for large-scale fabrication.
[0043] At step 216, the transistor 100 may be tested for performance. The testing may include an electrical testing, such as current-voltage (I-V) characterization, capacitance-voltage (C-V) analysis, and/or frequency response measurements may be performed to evaluate a switching speed, threshold voltage, and/or power efficiency of the transistor 100. The testing may further include thermal and reliability tests that may also be conducted to ensure long-term stability and/or robustness of the transistor 100 under varying operating conditions.
[0044] At step 218, the transistor 100 may be produced. Once the transistor 100 may have passed all quality control and/or the performance tests, the transistor 100 may be mass-produced for commercial or industrial applications. The transistor 100 may then be distributed for use in high-performance electronics, power devices, and/or radio-frequency (RF) applications.
[0045] While the invention has been described in connection with what is presently considered to be the most practical and various embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.
[0046] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined in the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements within substantial differences from the literal languages of the claims. , Claims:CLAIMS
I/We Claim:
1. A high-electron-mobility transistor (HEMT) (100), characterized in that the high-electron-mobility transistor (HEMT) (100) comprising:
a double-channel heterostructure stack (102), wherein the double-channel heterostructure stack (102) is selected from an Aluminum Nitride (AlN), a Gallium Nitride (GaN), an Aluminum Gallium Nitride (AlGaN), or a combination thereof;
a p-doped Gallium Nitride (GaN) gate (104) adapted to induce normally-off operation by creating a depletion region at the double-channel heterostructure stack (102);
a back-barrier (106) adapted for improved electron confinement in the double-channel heterostructure stack (102); and
a two-dimensional electron gas (2DEG) layer (108) adapted to be formed at a heterojunction interface of the double-channel heterostructure stack (102) to facilitate high carrier mobility and efficient current flow in the transistor (100).
2. The transistor (100) as claimed in claim 1, wherein the back-barrier (106) is adapted to reduce leakage in the double-channel heterostructure stack (102).
3. The transistor (100) as claimed in claim 1, wherein the back-barrier (106) is fabricated using an Indium Gallium Nitride (InGaN), an Aluminum Gallium Nitride (InGaN), or a combination thereof.
4. The transistor (100) as claimed in claim 1, wherein the back-barrier (106) is adapted to enhance polarization effects to increase a density of the two-dimensional electron gas (2DEG) layer (108) leading to improvement in electron mobility.
5. The transistor (100) as claimed in claim 1, wherein the p-doped Gallium Nitride (GaN) gate (104) effectively modulates the two-dimensional electron gas (2DEG) layer (108) and reduces gate leakage current, leading to enhanced threshold voltage control
6. The transistor (100) as claimed in claim 1, wherein the back-barrier (106) is adapted to improve current drive efficiency by confining electrons in a lower channel and reducing leakage to a buffer layer.
7. The transistor (100) as claimed in claim 1, wherein the double-channel heterostructure stack (102) is adapted to enhance carrier density resulting in higher saturation current and improved performance at high frequencies.
8. The transistor (100) as claimed in claim 1, wherein an integration of the double-channel heterostructure stack (102) and the back-barrier (106) enhances thermal stability, enabling reliable operation at high power levels.
9. The transistor (100) as claimed in claim 1, wherein an integration of the double-channel heterostructure stack (102) and the p-doped Gallium Nitride (GaN) gate (104) ensures low on-resistance and high drain current, making the transistor (100) suitable for power amplification applications.
10. A method (200) for fabrication of a high-electron-mobility transistor (HEMT) (100), the method is characterized by steps of:
depositing a double-channel heterostructure stack (102) on a substrate to form a two-dimensional electron gas (2DEG) layer (108) at a heterojunction interface;
forming a p-doped Gallium Nitride (GaN) gate (104) over the heterostructure to create a depletion region at a gate-channel interface for normally-off operation;
incorporating a back-barrier (106) beneath the heterostructure to confine electrons and reduce leakage current;
etching the p-doped Gallium Nitride (GaN) gate (104) to define a gate structure;
depositing and patterning source and drain electrodes to make ohmic contacts with the two-dimensional electron gas (2DEG) layer (108);
applying passivation layers to enhance the transistor (100) and protect against environmental effects; and
optimizing the transistor (100) to enhance carrier confinement, reduce gate leakage, and improve overall performance.
Date: March 28, 2025
Place: Noida

Nainsi Rastogi
Patent Agent (IN/PA-2372)
Agent for the Applicant