A transverse slot anode dual channel IMPATT diode and a method for manufacturing the same

Abstract

The application discloses a transverse groove anode double-channel IMPATT diode and a preparation method thereof. The diode comprises a substrate layer, an n-AlGaN back potential barrier layer on the substrate layer, left and right epitaxial layers on the n-AlGaN back potential barrier layer, left and right n-AlGaN potential barrier layers on the left and right epitaxial layers, left and right n+ GaN potential barrier layers, left and right ohmic contact layers on the n-AlGaN back potential barrier layer, left and right ohmic contact electrodes on the left and right ohmic contact layers, a passivation layer on the left and right n-AlGaN potential barrier layers and the left and right n+ GaN potential barrier layers, a Schottky contact electrode on the n-AlGaN back potential barrier layer, and a current direction along the left and right epitaxial layers in an on-state. Left and right drift layers are two-dimensional electron gas thin layers formed on top of the left and right epitaxial layers, and a transition process is limited in the left and right drift layers, so that the diode has high output power and working frequency.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically a transverse groove anode dual-channel IMPATT diode and its fabrication method. Background Technology

[0002] With the development of wide-bandgap semiconductor materials, especially gallium nitride (GaN), the operating frequency of electronic solid-state source devices can be extended to the millimeter-wave and even terahertz bands. Thanks to the use of wide-bandgap semiconductor materials, the power performance of the devices has also been greatly improved. Compared with resonant tunneling diodes (RTDs), Gunn diodes, and plasmawave devices, two-port impact-ionization avalanche transit time (IMPATT) diodes are the mainstream solution for realizing solid-state microwave and terahertz sources. This is because IMPATT has higher frequency, greater output power per unit area, and DC-RF conversion efficiency in terms of radio frequency (RF) characteristics such as high stability oscillation. The IMPATT diode is a semiconductor device that utilizes impact ionization in semiconductors to generate charge packets. The transit of these charge packets creates negative resistance at a certain frequency. Due to avalanche delay, the transit time of charge carriers within the device is also delayed. The superposition of these two delays causes the avalanche current to lag behind the terminal voltage, thus generating negative resistance. As the most efficient and highest-power microwave solid-state source, the IMPATT diode has received widespread attention for high-power solid-state source applications since its inception and is widely used in both military and civilian fields, such as communication and radar systems.

[0003] Compared to materials like Si and GaAs, GaN has attracted widespread attention due to its high thermal conductivity, high electron saturation velocity, and high breakdown voltage. It enables IMPATT diodes in the millimeter-wave and terahertz bands to achieve high output power, small size, and high reliability. In vertically structured IMPATT devices based on GaN, the operating frequency responds well to DC bias current density, allowing them to withstand higher DC bias current densities. Furthermore, they exhibit stronger negative resistance generation capability under high current, with a peak negative resistance significantly higher than that of GaAs-based devices. However, GaN's bandgap is too large at 3.4 eV, while the typical metal work function currently available in fabrication processes is generally around 4 to 5 eV, making it difficult to achieve a low metal-P-type GaN barrier height difference. Secondly, the free hole concentration in P-type doped GaN is too low. Even with a high doping level, it is difficult to obtain a high free hole concentration. In summary, in the traditional vertical GaN-based IMPATT, due to the immature manufacturing technology, it is difficult to form high-quality P-type ohmic contacts in P-type GaN, which limits the concentration of charge packets generated by collisional ionization, and thus severely restricts the working performance of the traditional vertical IMPATT.

[0004] like Figure 1 As shown, in a traditional vertical IMPATT diode, the current flows parallel to the epitaxial growth direction. Its working process is as follows: avalanche breakdown occurs in the avalanche region, generating electron-hole pairs, which then undergo a transit process in the drift region. In addition to the avalanche process affecting the working performance, the drift process is also crucial. In a traditional vertical IMPATT, the drift process occurs in the bulk material. As the device size increases, the electron drift distance increases, and the optimal operating frequency begins to decrease. In IMPATT, a transit time-effect device, the operating frequency is heavily dependent on the device size. The larger the size, the longer the drift time, and the lower the operating frequency. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a lateral grooved anode dual-channel IMPATT diode and its preparation method, which not only has high output power performance and operating frequency performance, but also has good compatibility with lateral circuits.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A transverse groove anode dual-channel IMPATT diode includes a substrate layer and an n-AlGaN back barrier layer located on the substrate layer. A left epitaxial layer and a right epitaxial layer are grown on the n-AlGaN back barrier layer. A left n-AlGaN barrier layer and a right n-AlGaN barrier layer are grown on the left epitaxial layer and the right epitaxial layer, respectively. When energized, a left drift layer is formed on the top of the left epitaxial layer and a right drift layer is formed on the top of the right epitaxial layer.

[0008] The n-AlGaN back barrier layer is further topped with a left n+-GaN barrier layer, a right n+-GaN barrier layer, a left ohmic contact layer, and a right ohmic contact layer. The left n+-GaN barrier layer is located to the right of the left epitaxial layer and the left n-AlGaN barrier layer, the right n+-GaN barrier layer is located to the left of the right epitaxial layer and the right n-AlGaN barrier layer, the left ohmic contact layer is located to the left of the left epitaxial layer and the left n-AlGaN barrier layer, and the right ohmic contact layer is located to the right of the right epitaxial layer and the right n-AlGaN barrier layer.

[0009] A left ohmic contact electrode is grown on the upper layer of the left ohmic contact layer, and a right ohmic contact electrode is grown on the upper layer of the right ohmic contact layer. The passivation layer is located on the upper layers of the left n-AlGaN barrier layer, the right n-AlGaN barrier layer, the left n+-GaN barrier layer, and the right n+-GaN barrier layer. The Schottky contact electrode is located on the upper layer of the n-AlGaN back barrier layer and between the left n+-GaN barrier layer and the right n+-GaN barrier layer. When energized, the current direction is transverse along the left epitaxial layer and the right epitaxial layer. The left drift layer and the right drift layer are two-dimensional electron gas thin layers formed on the top of the left epitaxial layer and the right epitaxial layer, respectively, when energized. The transit process is confined in the left drift layer and the right drift layer and does not occur in the bulk material.

[0010] Furthermore, the n-AlGaN back barrier layer is an n-AlGaN with a thickness of 100–1000 nm and an Al molar percentage of 3%–15%. The n-AlGaN is undoped, and the background doping concentration is no greater than 1 × 10⁻⁶. 15 cm -3 .

[0011] Furthermore, the left and right epitaxial layers are i-GaN with a thickness of 50–80 nm.

[0012] Furthermore, the left and right n-AlGaN barrier layers have a thickness of 60–120 nm, an Al molar percentage of 20%–60%, and a doping concentration of 5 × 10⁻⁶. 16 ~1×10 17 cm -3 n-AlGaN.

[0013] Furthermore, both the left n+-GaN barrier layer and the right n+-GaN barrier layer have a thickness of 100–200 nm and a doping concentration of 5 × 10⁻⁶. 17 ~1×10 18 cm -3 n+-GaN.

[0014] Furthermore, the left and right ohmic contact layers have a thickness of 100–200 nm and a doping concentration of 5 × 10⁻⁶. 17 ~1×10 18 cm -3 n++-GaN.

[0015] Furthermore, the left ohmic contact electrode and the right ohmic contact electrode comprise Ti, Al, Pt and Au metal layers with a total thickness of 20–50 nm.

[0016] Furthermore, the relative permittivity of the passivation layer ranges from 10 to 200, and its thickness is equal to the thickness of the left or right ohmic contact electrode.

[0017] Furthermore, the Schottky contact electrode comprises Ni and Au metal layers with a total thickness of 120–200 nm.

[0018] A method for assembling a lateral grooved anode dual-channel IMPATT diode includes the following steps:

[0019] S1. Select sapphire material as the initial material to form the substrate layer;

[0020] S2. An n-AlGaN back barrier layer is formed on the upper layer of the substrate;

[0021] S3. An i-GaN epitaxial layer is formed on top of the n-AlGaN back barrier layer;

[0022] S4. An n-AlGaN barrier layer is formed on top of the i-GaN epitaxial layer;

[0023] S5, Etch the n-AlGaN barrier layer and the i-GaN epitaxial layer;

[0024] S6. Grow a left ohmic contact layer and a right ohmic contact layer on the n-AlGaN back barrier layer;

[0025] S7. Etch the n-AlGaN barrier layer and the i-GaN epitaxial layer, dividing the n-AlGaN barrier layer into a left n-AlGaN barrier layer and a right n-AlGaN barrier layer, and the i-GaN epitaxial layer into a left epitaxial layer and a right epitaxial layer.

[0026] S8. An n+-GaN barrier layer is grown on the n-AlGaN back barrier layer between the left epitaxial layer and the right epitaxial layer. At the same time, the n+-GaN barrier layer is located between the left n-AlGaN barrier layer and the right n-AlGaN barrier layer.

[0027] S9. Etch the n+-GaN barrier layer to form the first groove, which divides the n+-GaN barrier layer into a left n+-GaN barrier layer and a right n+-GaN barrier layer.

[0028] S10. Left ohmic contact electrode and right ohmic contact electrode are formed on the upper layers of the left ohmic contact layer and the right ohmic contact layer, respectively. Passivation layer is formed on the upper layers of the left n-AlGaN barrier layer, the right n-AlGaN barrier layer, the left n+-GaN barrier layer and the right n+-GaN barrier layer.

[0029] S11. The passivation layer is etched to form a second groove that communicates with the first groove. Schottky contact electrodes are formed in the first and second grooves on the n-AlGaN back barrier layer. When energized, a left drift layer is formed on the top of the left epitaxial layer and a right drift layer is formed on the top of the right epitaxial layer.

[0030] Compared with the prior art, the present invention has the following technical effects:

[0031] The lateral groove anode dual-channel IMPATT diode of the present invention has the following three advantages: (1) In the AlGaN / GaN heterostructure of the lateral groove anode dual-channel IMPATT diode of the present invention, due to the discontinuity of potential and the inconsistency of material band gap, there is a large band discontinuity. Even under a high bias voltage, the two-dimensional electron gas can still be well confined in the quantum well. Furthermore, the introduction of the n-AlGaN back barrier layer further enhances the confinement threshold of the two-dimensional electron gas, so that electrons can be distributed relatively uniformly in the two-dimensional electron gas channel layer, which greatly promotes the charge packet transition process. The high concentration of two-dimensional electron gas in the channel greatly improves the power of the device, allows the device size to be greatly reduced, and helps to break through the bottleneck of Moore's Law. (2) Given that there is no mature process technology for vertical structure IMPATT devices, it is difficult to obtain a high doping concentration in the P region of the vertical structure IMPATT diode, which makes the series resistance of the vertical structure IMPATT diode more significant. The P-type GaN ohmic contact resistance can only be controlled at 10. -4 ~10 -5 Ω·cm 2The technical problem of performance limitations in vertical IMPATT diodes due to the order-of-magnitude difference in doping between GaN and P-type materials is addressed in this invention. At the device structure level, the limitations of P-type doping in GaN materials are solved. In the lateral structure IMPATT diode, the epitaxial layer grows from bottom to top, with the current direction perpendicular to the growth direction of the epitaxial layer. The drift layer utilizes a two-dimensional electron gas, confining the transit process within a thin layer rather than in the bulk material, thus optimizing the charge packet transit process. The high concentration of two-dimensional electron gas in the channel layer significantly improves the device power, achieving extremely high operating frequencies without using highly doped P-type contacts. As the size of the n-AlGaN barrier layer in the lateral structure IMPATT diode decreases, the electric field under the n-AlGaN barrier layer also increases, promoting electron valley transfer. Simultaneously, electrons move almost like ballistic transport, exhibiting high drift velocities, thereby greatly increasing the oscillation frequency of the IMPATT diode. This facilitates its operation in the millimeter-wave and even terahertz bands, resulting in higher output power and operating frequency performance. (3) For traditional vertical IMPATT diodes, each independent vertical IMPATT structure needs to be packaged in a cavity if it is to be mass-produced. However, the horizontal IMPATT diode can be combined with high-capacity devices to improve power output performance and has excellent compatibility with horizontal circuits. For example, based on coplanar waveguide (CPW) components, qualified chips can be manufactured on an independent wafer using photolithography. As a microwave oscillation source, the horizontal IMPATT diode can be seamlessly connected with a monolithic microwave integrated circuit (MMIC) to form a radio frequency output system in the millimeter wave or even terahertz band, which significantly improves productivity and repetition rate. It is suitable for mass production and application as a microwave oscillation source.

[0032] When the lateral groove anode dual-channel IMPATT diode of the present invention undergoes avalanche breakdown under an applied bias, due to the strong piezoelectric polarization and spontaneous polarization effect of the AlGaN / GaN heterojunction, a concentration >10 is formed at the heterojunction interface. 19 cm -3 The two-dimensional electron gas, i.e. the drift layer, is generally undoped because the n-AlGaN back barrier layer and the i-GaN epitaxial layer are usually undoped. Therefore, electrons in the drift layer are far away from ionized donors, and ionized impurity scattering is greatly reduced. Electrons are more easily heated by an external electric field to obtain enough energy to jump to a higher energy valley. The reduction of ionized impurity scattering also enhances the low-field mobility of electrons, thereby increasing the peak-to-valley ratio in the velocity-field relationship, making the negative differential mobility effect of the IMPATT device more significant.

[0033] This invention divides the drift layer on top of the epitaxial layer into a left drift layer and a right drift layer by etching the n-AlGaN barrier layer and the i-GaN epitaxial layer. This allows the distance between the Schottky contact electrode and the left and right ohmic contact electrodes to be adjusted by changing the groove position, making the oscillation frequency and output power of the device flexibly adjustable. In contrast, in traditional vertical IMPATT diodes, once the wafer is grown, the spacing between the anode and cathode is fixed, thus the oscillation frequency of the vertical IMPATT diode remains constant. In this invention, the spacing between the anode and cathode of the lateral groove electrode dual-channel IMPATT diode is adjustable after growth, offering not only high design flexibility but also flexible adjustment of the IMPATT operating frequency band. When the spacing between the anode and cathode of the IMPATT diode is reduced to a submicron length, flexible adjustment from the submillimeter band to the low terahertz band can be achieved, thereby manufacturing a flexible and controllable IMPATT RF chip based on a lateral structure. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a traditional vertical IMPATT diode.

[0035] Figure 2 This is a schematic diagram of the die cross-sectional structure of the transverse groove anode dual-channel IMPATT diode of the present invention;

[0036] Figure 3 This is a flowchart illustrating the fabrication method of the transverse groove anode dual-channel IMPATT diode of the present invention.

[0037] Figure 4 This is a detailed process flow diagram of the fabrication method of the transverse groove anode dual-channel IMPATT diode of the present invention;

[0038] In the figure: 1. Substrate layer; 2. n-AlGaN back barrier layer; 3. Left epitaxial layer; 4. Right epitaxial layer; 5. Left drift layer; 6. Right drift layer; 7. Left n-AlGaN barrier layer; 8. Right n-AlGaN barrier layer; 9. Left n+-GaN barrier layer; 10. Right n+-GaN barrier layer; 11. Left ohmic contact layer; 12. Right ohmic contact layer; 13. Left ohmic contact electrode; 14. Right ohmic contact electrode; 15. Passivation layer; 16. Schottky contact electrode. Detailed Implementation

[0039] The specific content of the present invention will be further explained in detail below with reference to the embodiments.

[0040] like Figure 2As shown, a transverse groove anode dual-channel IMPATT diode includes a substrate layer 1, an n-AlGaN back barrier layer 2, a left epitaxial layer 3, a right epitaxial layer 4, a left drift layer 5, a right drift layer 6, a left n-AlGaN barrier layer 7, a right n-AlGaN barrier layer 8, a left n+-GaN barrier layer 9, a right n+-GaN barrier layer 10, a left ohmic contact layer 11, a right ohmic contact layer 12, a left ohmic contact electrode 13, a right ohmic contact electrode 14, a passivation layer 15, and a Schottky contact anode 16.

[0041] The n-AlGaN back barrier layer 2 is located on the substrate layer 1. The left epitaxial layer 3 and the right epitaxial layer 4 are located on the n-AlGaN back barrier layer 2. The left n-AlGaN barrier layer 7 and the right n-AlGaN barrier layer 8 are located on the left epitaxial layer 3 and the right epitaxial layer 4, respectively. The left n+-GaN barrier layer 9 is located on the n-AlGaN back barrier layer 2, and is located to the right of the left epitaxial layer 3 and the left n-AlGaN barrier layer 7. The right n+-GaN barrier layer 10 is located on the n-AlGaN back barrier layer 2, and is located to the left of the right epitaxial layer 4 and the right n-AlGaN barrier layer 8. The left ohmic contact layer 11 and the right ohmic contact layer 12 are both located on the n-AlGaN back barrier layer 2. The left ohmic contact layer 11 is located on the left side of the left epitaxial layer 3 and the left n-AlGaN barrier layer 7, and the right ohmic contact layer 12 is located on the right side of the right epitaxial layer 4 and the right n-AlGaN barrier layer 7. The left ohmic contact electrode 13 is located on the left ohmic contact layer 11, and the right ohmic contact electrode 14 is located on the right ohmic contact layer 12. The passivation layer 15 is located on the left n-AlGaN barrier layer 7, the right n-AlGaN barrier layer 8, the left n+-GaN barrier layer 9, and the right n+-GaN barrier layer 10. The Schottky contact electrode 16 is located on the n-AlGaN back barrier layer 2, and the Schottky contact electrode is located between the left n+-GaN barrier layer 9 and the right n+-GaN barrier layer 10.

[0042] When the transverse groove anode dual-channel IMPATT diode is energized, the current direction is transverse along the left epitaxial layer 3 and the right epitaxial layer 4. The left drift layer 5 and the right drift layer 6 are two-dimensional electron gas thin layers formed on the top of the left epitaxial layer 3 and the right epitaxial layer 4 respectively when energized. The left drift layer 5 is located at the junction of the left epitaxial layer 3 and the left n-AlGaN barrier layer 7, and is closer to the top of the left epitaxial layer 3. The right drift layer 6 is located at the junction of the right epitaxial layer 4 and the right n-AlGaN barrier layer 8, and is closer to the top of the right epitaxial layer 4. The transition process is confined to the left drift layer 5 and the right drift layer 6 rather than occurring in the bulk material.

[0043] Preferably, the left ohmic contact layer 11 and the right ohmic contact layer 12 are made of n++-GaN, with a thickness of 100-200 nm and a doping concentration of 5×10⁻⁶.17 ~1×10 18 cm -3 .

[0044] Preferably, the left n+-GaN barrier layer 9 and the right n+-GaN barrier layer 10 are made of n+-GaN, with a thickness of 100-200 nm and a doping concentration of 5 × 10⁻⁶. 17 ~1×10 18 cm -3 .

[0045] Preferably, the material of the left epitaxial layer 3 and the right epitaxial layer 4 is i-GaN, and the thickness is 50-80 nm.

[0046] Preferably, the n-AlGaN back barrier layer 2 is made of n-AlGaN with a thickness of 100–1000 nm, and the molar percentage of Al is 3%–15%. The n-AlGaN material is free of intentional doping, and the background doping concentration is less than or equal to 1 × 10⁻⁶. 15 cm -3 .

[0047] Preferably, the left n-AlGaN barrier layer 7 and the right n-AlGaN barrier layer 8 are made of n-AlGaN, with a thickness of 60–120 nm, an Al molar percentage of 20%–60%, and a doping concentration of 5 × 10⁻⁶. 16 ~1×10 17 cm -3 .

[0048] Preferably, the left ohmic contact electrode 13 and the right ohmic contact electrode 14 comprise Ti, Al, Pt and Au metal layers with a total thickness of 20-50 nm.

[0049] Preferably, the relative permittivity of the passivation layer 15 is in the range of 10 to 200, and its thickness is equal to the thickness of the left ohmic contact electrode 13 or the right ohmic contact electrode 14.

[0050] Preferably, the Schottky contact electrode 16 comprises Ni and Au metal layers with a total thickness of 120–200 nm.

[0051] like Figure 3 As shown, a method for fabricating a lateral grooved anode dual-channel IMPATT diode includes the following steps:

[0052] S1. Select sapphire material as the initial material to form substrate layer 1;

[0053] S2. An n-AlGaN back barrier layer 2 is formed on the substrate layer 1;

[0054] S3. An i-GaN epitaxial layer is formed on the n-AlGaN back barrier layer 2;

[0055] S4. An n-AlGaN barrier layer is formed on top of the i-GaN epitaxial layer;

[0056] S5, Etch the n-AlGaN barrier layer and the i-GaN epitaxial layer;

[0057] S6. Grow a left ohmic contact layer 11 and a right ohmic contact layer 12 on the n-AlGaN back barrier layer 2.

[0058] S7. Etch the n-AlGaN barrier layer and the i-GaN epitaxial layer, dividing the n-AlGaN barrier layer into the left n-AlGaN barrier layer 7 and the right n-AlGaN barrier layer 8, and the i-GaN epitaxial layer into the left epitaxial layer 3 and the right epitaxial layer 4.

[0059] S8. An n+-GaN barrier layer is grown on the n-AlGaN back barrier layer 2 between the left epitaxial layer 3 and the right epitaxial layer 4. At the same time, the n+-GaN barrier layer is located between the left n-AlGaN barrier layer 7 and the right n-AlGaN barrier layer 8.

[0060] S9. Etch the n+-GaN barrier layer to form the first groove, which divides the n+-GaN barrier layer into the left n+-GaN barrier layer 9 and the right n+-GaN barrier layer 10.

[0061] S10. Left ohmic contact electrode 13 and right ohmic contact electrode 14 are formed on the left ohmic contact layer 11 and right ohmic contact layer 12 respectively, and passivation layer 15 is formed on the left n-AlGaN barrier layer 7, right n-AlGaN barrier layer 8, left n+-GaN barrier layer 9 and right n+-GaN barrier layer 10.

[0062] S11, the etched passivation layer 15 forms a second groove that communicates with the first groove. Schottky contact electrode 16 is formed in the first and second grooves on the n-AlGaN back barrier layer 2. When energized, a left drift layer 5 is formed on the top of the left epitaxial layer 3, and a right drift layer 6 is formed on the top of the right epitaxial layer 4.

[0063] like Figure 4 As shown, the specific fabrication process of a lateral groove anode dual-channel IMPATT diode is as follows:

[0064] Step 1: Substrate 1 is made of sapphire material. Cleaning substrate 1: Etch in a solution with a molar ratio of H2SO4:H2Po4 = 3:1 for 20 minutes, rinse with deionized water, and dry with N2.

[0065] Step 2, Preheating of Substrate 1: Ammoniation is completed at 800℃ in an ammonia stream for 5-15 minutes;

[0066] Step 3: Deposit n-AlGaN back barrier layer 2: The temperature of substrate 1 is 800℃, the aluminum source temperature is 1070℃, and the nitrogen source ammonia flow rate is 16S CCM. Metal-organic chemical vapor deposition (MOCVD) is used. The reaction chamber temperature is set to 1050℃, and the reaction chamber pressure is increased to 100 Torr. Simultaneously, trimethylgallium, nitrogen, and trimethylaluminum are introduced into the reaction chamber. An n-AlGaN back barrier layer 2 with a thickness of 100–1000 nm is grown on substrate 1. The n-AlGaN material is undoped, and its background doping concentration is less than or equal to 1 × 10⁻⁶. 15 cm -3 The Al component is 3-15%;

[0067] Step 4, n-GaN growth: Triethylgallium and high-purity nitrogen were used as the gallium source and nitrogen source, respectively. The substrate temperature was lowered to 700℃, the gallium source temperature was 970℃, and the ammonia flow rate was 35 SCCM (5 × 10⁻⁶ ppm). 16 cm -3 Under the condition of an internal pressure of 40 Torr in the reaction chamber, an i-GaN epitaxial layer was formed by epitaxially depositing a 50-80 nm thick GaN layer on the back barrier layer 2 using the metal-organic chemical vapor deposition (MOCVD) method.

[0068] Step 5: Maintain the reaction chamber temperature at 1050℃, increase the reaction chamber pressure to 100 Torr, and simultaneously introduce trimethylgallium, nitrogen, and trimethylaluminum into the reaction chamber. Epitaxially grow a layer on top of the epitaxial layer with a thickness of 60–120 nm and a doping concentration of 5 × 10⁻⁶. 16 ~1×10 17 cm -3 n-AlGaN with an Al molar percentage of 20% to 60% forms an n-AlGaN barrier layer;

[0069] Step 6: Photolithography forms circular mask patterns with diameters of 10 μm and 15 μm on the n-GaN layer. Using reactive ion etching (RIE), a BCl3 / Cl2 gas etching source is used to etch the n-AlGaN barrier layer and the i-GaN epitaxial layer to form left and right ohmic contact regions. The etching depth reaches the upper surface of the n-AlGaN back barrier layer 2.

[0070] Step 7: Doping the device by ion implantation to grow n++-GaN left ohmic contact layer 11 and right ohmic contact layer 12 located on the left and right sides of the n-AlGaN barrier layer and the i-GaN epitaxial layer, respectively, with a doping concentration of 5×10⁻⁶. 17 ~1×10 18 cm -3 ;

[0071] Step 8: Photolithography is used to form a small circular mask pattern with a diameter of 5-8 μm on the n-AlGaN barrier layer. The reactive ion etching (RIE) method is then used to etch the n-AlGaN barrier layer and the i-GaN epitaxial layer using a BCl3 / Cl2 gas etching source. The n-AlGaN barrier layer is divided into a left n-AlGaN barrier layer 7 and a right n-AlGaN barrier layer 8, and the i-GaN epitaxial layer is divided into a left i-GaN epitaxial layer 3 and a right i-GaN epitaxial layer 4. The etching depth reaches the upper surface of the n-AlGaN back barrier layer 2.

[0072] Step 9: Dope the device by ion implantation to grow an n+-GaN barrier layer with a doping concentration of 5×10⁻⁶. 17 ~1×10 18 cm -3 .

[0073] Step 10: Photolithography is used to form a small circular mask pattern with a diameter of 2-5 μm on the n+-GaN barrier layer. The reactive ion etching (RIE) method is then used to etch the n+-GaN barrier layer using a BCl3 / Cl2 gas etching source. The first groove formed by etching divides the n+-GaN barrier layer into a left n+-GaN barrier layer 9 and an n+-GaN barrier layer 10.

[0074] Step 11: On the stepped annular mesa formed by the epitaxial layer and the ohmic contact layer, Ti, Al, Pt and Au metal layers are sequentially evaporated using a vacuum electron beam evaporation device, with thicknesses of 15nm, 50nm, 30nm and 30nm respectively. Then, the metal is peeled off to form annular left ohmic contact electrode 13 and right ohmic contact electrode 14. Next, rapid thermal annealing is performed at 750℃ for 3 minutes, with nitrogen as the annealing gas, to form an ohmic contact.

[0075] Step 12: Using an RF magnetron sputtering device, a Si3N4 layer with a thickness of 570 nm and a width of 15 nm is sputtered onto the left n-AlGaN barrier layer 7, the right n-AlGaN barrier layer 8, the left n+-GaN barrier layer 9, and the right n+-GaN barrier layer 10 to form a passivation layer 10. The sputtering process conditions are: RF power of 100 W, target spacing of 20 cm, and when the reaction chamber pressure is 0.4 Pa, argon, oxygen, and nitrogen are introduced, with a nitrogen flow rate of 20%. The purpose of introducing oxygen is to generate a small amount of SiO2, so that the passivation layer 10 includes both Si3N4 and SiO2 materials.

[0076] Step 13: Etch the passivation layer 15 to form a second groove that communicates with the first groove. In the first and second grooves on the n-AlGaN back barrier layer 2, Ni and Au bilayer metals are evaporated sequentially using a vacuum electron beam evaporation device, with thicknesses of 50 nm and 100 nm, respectively. After metal stripping, an annular Schottky barrier electrode 16 is formed.

Claims

1. A transverse grooved anode dual-channel IMPATT diode, characterized in that, It includes a substrate layer (1) and an n-AlGaN back barrier layer (2) located on the substrate layer (1). A left epitaxial layer (3) and a right epitaxial layer (4) are grown on the n-AlGaN back barrier layer (2). A left n-AlGaN barrier layer (7) and a right n-AlGaN barrier layer (8) are grown on the left epitaxial layer (3) and the right epitaxial layer (4), respectively. When the power is applied, a left drift layer (5) is formed on the top of the left epitaxial layer (3) and a right drift layer (6) is formed on the top of the right epitaxial layer (4). The n-AlGaN back barrier layer (2) is further covered by a left n+-GaN barrier layer (9), a right n+-GaN barrier layer (10), a left ohmic contact layer (11), and a right ohmic contact layer (12). The left n+-GaN barrier layer (9) is located to the right of the left epitaxial layer (3) and the left n-AlGaN barrier layer (7), the right n+-GaN barrier layer (10) is located to the left of the right epitaxial layer (4) and the right n-AlGaN barrier layer (8), the left ohmic contact layer (11) is located to the left of the left epitaxial layer (3) and the left n-AlGaN barrier layer (7), and the right ohmic contact layer (12) is located to the right of the right epitaxial layer (4) and the right n-AlGaN barrier layer (8). A left ohmic contact electrode (13) is grown on the left ohmic contact layer (11), and a right ohmic contact electrode (14) is grown on the right ohmic contact layer (12). A passivation layer (15) is located on the left n-AlGaN barrier layer (7), the right n-AlGaN barrier layer (8), the left n+-GaN barrier layer (9), and the right n+-GaN barrier layer (10). A Schottky contact electrode (16) is located on the n-AlGaN back barrier. Between the upper layer (2) and the left n+-GaN barrier layer (9) and the right n+-GaN barrier layer (10), the current direction when energized is along the transverse direction of the left epitaxial layer (3) and the right epitaxial layer (4). The left drift layer (5) and the right drift layer (6) are two-dimensional electron gas thin layers formed on the top of the left epitaxial layer (3) and the right epitaxial layer (4) respectively when energized. The transit process is confined in the left drift layer (5) and the right drift layer (6) rather than occurring in the bulk material.

2. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, The n-AlGaN back barrier layer (2) is an n-AlGaN with a thickness of 100-1000 nm and an Al molar percentage of 3%-15%. The n-AlGaN is not intentionally doped, and the background doping concentration is no greater than 1×10⁻⁶. 15 cm -3 .

3. The IMPATT diode with a transverse grooved anode as described in claim 1, characterized in that, The left epitaxial layer (3) and the right epitaxial layer (4) are i-GaN with a thickness of 50-80 nm.

4. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, The left n-AlGaN barrier layer (7) and the right n-AlGaN barrier layer (8) have a thickness of 60–120 nm, an Al molar percentage of 20%–60%, and a doping concentration of 5 × 10⁻⁶. 16 ~1×10 17 cm -3 n-AlGaN.

5. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, Both the left n+-GaN barrier layer (9) and the right n+-GaN barrier layer (10) have a thickness of 100-200 nm and a doping concentration of 5 × 10⁻⁶. 17 ~1×10 18 cm -3 n+-GaN.

6. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, The left ohmic contact layer (11) and the right ohmic contact layer (12) have a thickness of 100-200 nm and a doping concentration of 5 × 10⁻⁶. 17 ~1×10 18 cm -3 n++-GaN.

7. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, The left ohmic contact electrode (13) and the right ohmic contact electrode (14) include Ti, Al, Pt and Au metal layers with a total thickness of 20-50 nm.

8. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, The passivation layer (15) has a relative permittivity in the range of 10 to 200, and its thickness is equal to the thickness of the left ohmic contact electrode (13) or the right ohmic contact electrode (14).

9. The transverse grooved anode dual-channel IMPATT diode according to claim 1, characterized in that, The Schottky contact electrode (16) comprises Ni and Au metal layers with a total thickness of 120–200 nm.

10. A method for fabricating a transverse grooved anode dual-channel IMPATT diode as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Select sapphire material as the initial material to form a substrate layer (1); S2. An n-AlGaN back barrier layer (2) is formed on the substrate layer (1); S3. An i-GaN epitaxial layer is formed on the n-AlGaN back barrier layer (2); S4. An n-AlGaN barrier layer is formed on top of the i-GaN epitaxial layer; S5, Etch the n-AlGaN barrier layer and the i-GaN epitaxial layer; S6. A left ohmic contact layer (11) and a right ohmic contact layer (12) are grown on the n-AlGaN back barrier layer (2); S7. Etch the n-AlGaN barrier layer and the i-GaN epitaxial layer, divide the n-AlGaN barrier layer into a left n-AlGaN barrier layer (7) and a right n-AlGaN barrier layer (8), and divide the i-GaN epitaxial layer into a left epitaxial layer (3) and a right epitaxial layer (4). S8. An n+-GaN barrier layer is grown on the n-AlGaN back barrier layer (2) between the left epitaxial layer (3) and the right epitaxial layer (4), and the n+-GaN barrier layer is located between the left n-AlGaN barrier layer (7) and the right n-AlGaN barrier layer (8). S9. Etch the n+-GaN barrier layer to form the first groove, which divides the n+-GaN barrier layer into the left n+-GaN barrier layer (9) and the right n+-GaN barrier layer (10). S10. Left ohmic contact electrode (13) and right ohmic contact electrode (14) are formed on the left ohmic contact layer (11) and right ohmic contact layer (12) respectively. Passivation layer (15) is formed on the left n-AlGaN barrier layer (7), right n-AlGaN barrier layer (8), left n+-GaN barrier layer (9) and right n+-GaN barrier layer (10). S11, Etching the passivation layer (15) forms a second groove that communicates with the first groove. A Schottky contact electrode (16) is formed in the first and second grooves above the n-AlGaN back barrier layer (2). When energized, a left drift layer (5) is formed on the top of the left epitaxial layer (3), and a right drift layer (6) is formed on the top of the right epitaxial layer (4).

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