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CN-121985557-A - GaN HEMT device with adjustable threshold voltage structure

CN121985557ACN 121985557 ACN121985557 ACN 121985557ACN-121985557-A

Abstract

The invention belongs to the technical field of semiconductors, and relates to a GaN HEMT device with an adjustable threshold voltage structure. In the invention, a PNP triode structure is led in a grid electrode, wherein an N-terminal leading-out electrode is used as a threshold control electrode, and a P-terminal leading-out electrode at the top layer is used as the grid electrode. The gate voltage of the entire device must exceed the threshold control electrode voltage plus the voltage at which the top PN junction opens to open the device channel. Meanwhile, due to hole injection brought by the BJT structure, the structure also has a conductivity modulation effect, so that the transconductance of the device can be improved, and the grid control capability is enhanced. The invention has the externally given threshold control electrode, so that the device can realize adjustable threshold voltage, and different threshold voltages can be realized by applying different voltages through the threshold control electrode.

Inventors

  • LI YOU
  • DU JIANGFENG
  • ZHAO YAPENG
  • LIU CHENGYI
  • HU JINWEI

Assignees

  • 电子科技大学
  • 电子科技大学广东电子信息工程研究院

Dates

Publication Date
20260505
Application Date
20260309

Claims (10)

  1. 1. A GaN HEMT device with an adjustable threshold voltage structure comprises a substrate (01), a transition layer (02), a buffer layer (03), a channel layer (04) and a barrier layer (05) which are sequentially stacked from bottom to top along the vertical direction of the device, wherein the channel layer (04) and the barrier layer (05) form a heterojunction, a 2DEG is formed at a heterojunction interface, source metal (06), a gate structure and drain metal (07) are sequentially arranged on the surface of the device from left to right along the transverse direction, the source metal (06) is positioned at the leftmost end of the device and above the channel layer (04) and penetrates through the barrier layer (05) and part of the channel layer (04), the drain metal (07) is positioned at the rightmost end of the device and above the channel layer (04) and penetrates through the barrier layer (05) and part of the channel layer (04); The gate structure is characterized in that the gate structure is formed by a PNP triode stack structure between source metal (06) and drain metal (07), and is a P-type GaN layer (08) on the upper surface of a barrier layer (05), an N-type GaN layer (09) on the upper surface or in a body of the P-type GaN layer (08), and a P-type GaN layer (10) on the upper surface or in the body of the N-type GaN layer (09), wherein a threshold control electrode metal (12) is arranged above the N-type GaN layer (09), the threshold control electrode metal 12 is not contacted with the P-type GaN layer 08, a gate metal (11) is manufactured on the P-type GaN layer (10), and the gate metal (11) and the threshold control electrode metal (12) are different electrodes and are not contacted; The whole device grid voltage exceeds the threshold control electrode voltage plus the starting voltage of the top PN junction to open the device channel, and meanwhile, the grid structure is used as a BJT grid structure and has a conductivity modulation effect.
  2. 2. The GaN HEMT device with adjustable threshold voltage structure of claim 1, wherein the substrate (01) material is one of Si, sapphire, siC, gaN, and QST.
  3. 3. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the transition layer (02) is made of one or more of gallium nitride, aluminum nitride and aluminum gallium nitride.
  4. 4. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the buffer layer (03) is made of one or more of gallium nitride, aluminum nitride and aluminum gallium nitride, and the doping element is carbon or iron, and the thickness is 1-10 um.
  5. 5. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the barrier layer (05) is made of one or more of gallium nitride, aluminum nitride and aluminum gallium nitride, and has a thickness of 5-100 nm.
  6. 6. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the P-type GaN layer (08) is made of P-type doped gallium nitride, aluminum nitride or aluminum gallium nitride, has doping concentration of 1X 10 17 ~5×10 20 cm -3 , has thickness of 10-500 nm, and is complete or comb-shaped in the width W direction of the device.
  7. 7. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the N-type GaN layer (09) is made of N-type doped gallium nitride, aluminum nitride or aluminum gallium nitride, has doping concentration of 1X10 10 ~5×10 20 cm -3 and thickness of 10-500 nm, is positioned on the upper surface or in the body of the P-type GaN layer (08), and is complete or comb-shaped in the width W direction of the device.
  8. 8. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the material adopted by the P-type GaN layer (10) is P-type doped gallium nitride, aluminum nitride or aluminum gallium nitride, the doping concentration is 1X 10 10 ~5×10 20 cm -3 , and the thickness is 10-500 nm.
  9. 9. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the contact between the gate metal (11) and the P-type GaN layer (10) is Schottky contact or ohmic contact, and the gate metal (11) is made of any one of Pt/Au, W/Au and Ni/Au.
  10. 10. The GaN HEMT device with the adjustable threshold voltage structure of claim 1, wherein the electrode material adopted by the threshold control electrode metal (12) is one or more of metal Ni, al, au, pt or Ti, and the position can be located at any position around a grid electrode capable of enabling the N-type GaN layer (09) to obtain corresponding potential and exists continuously or discontinuously.

Description

GaN HEMT device with adjustable threshold voltage structure Technical Field The invention belongs to the technical field of semiconductors, and relates to a GaN HEMT device with an adjustable threshold voltage structure. Background Gallium nitride (GaN) materials are receiving attention because of their physical properties such as high critical breakdown field, high electron mobility, high saturation velocity, and high two-dimensional electron gas (2 DEG) concentration. The current GaN HEMT is already applied to important fields such as fast charging, data centers, electric automobiles, power transportation and the like. At present, the main method for realizing the normally-off AlGaN/GaN HEMT comprises the technologies of a p-GaN covering layer, a thin barrier layer, a trench gate structure, fluorine ion implantation and the like. The p-GaN covering layer is the most mainstream technical route at present, and the working principle is that when the grid electrode is not externally biased, the energy band position of the AlGaN barrier layer is lifted by the existence of the p-GaN layer, so that the conduction band of a channel region is higher than the Fermi level, and the two-dimensional electron gas (2 DEG) is exhausted, and the device is ensured to be in a normally-closed state. However, the currently reported p-GaN gate HEMT still faces the problem of low threshold voltage, the threshold voltage of the GaN HEMT device using the p-GaN cap layer technology is only 1-2 v, and the parasitic effect may cause false turn-on during high-speed switching. And once the device design is finished, the threshold voltage is fixed and cannot be adjusted by an external circuit. Disclosure of Invention Aiming at the problems or the defects, the invention provides a GaN HEMT device with an adjustable threshold voltage structure, which aims to solve the problems that the current threshold voltage of the GaN HEMT device is low and cannot be adjusted. On the basis of the original GaN HEMT, the PNP structure is used in the grid structure, and an independent threshold control electrode is led out. The structure realizes the enhancement effect through the P-GaN at the lower layer, and meanwhile, the grid voltage of the device can be opened only by exceeding the voltage of the threshold control electrode and the voltage for opening the PN junction at the top, so that the threshold voltage is improved and is adjustable. Because of the hole injection brought by the BJT structure, the structure of the invention also has the effect of conducting modulation, can improve the transconductance of the device and enhance the grid control capability. The invention has the externally given threshold control electrode, so that the device can realize adjustable threshold voltage, and different threshold voltages can be realized by applying different voltages through the threshold control electrode. In order to achieve the above purpose, the technical scheme of the invention is as follows: A GaN HEMT device with an adjustable threshold voltage structure comprises a substrate 01, a transition layer 02, a buffer layer 03, a channel layer 04 and a barrier layer 05 which are sequentially stacked from bottom to top along the vertical direction of the device. The channel layer 04 and the barrier layer 05 form a heterojunction, a 2DEG is formed at the heterojunction interface, the surface of the device is provided with source metal 06, a gate structure and drain metal 07 in sequence from left to right along the transverse direction, the source metal 06 is positioned at the leftmost end of the device and above the channel layer 04 and penetrates through the barrier layer 05 and part of the channel layer 04, the drain metal 07 is positioned at the rightmost end of the device and above the channel layer 04 and penetrates through the barrier layer 05 and part of the channel layer 04. The gate structure is formed by stacking a PNP triode between a source metal 06 and a drain metal 07, and comprises a P-type GaN layer 08 on the upper surface of a barrier layer 05, an N-type GaN layer 09 on the upper surface or in a body of the P-type GaN layer 08, and a P-type GaN layer 10 on the upper surface or in a body of the N-type GaN layer 09, wherein a threshold control electrode metal 12 is arranged above the N-type GaN layer 09, the threshold control electrode metal 12 is not contacted with the P-type GaN layer 08, a gate metal 11 is manufactured on the P-type GaN layer 10, and the gate metal 11 and the threshold control electrode metal 12 are different electrodes and are not contacted. The whole device grid voltage exceeds the threshold control electrode voltage plus the starting voltage of the top PN junction to open the device channel, and meanwhile, the grid structure is used as a BJT grid structure and has a conductivity modulation effect. Further, the substrate 01 is one of Si, sapphire, siC, gaN and QST. Further, the material adopted by the transition layer