阅读说明：本技术 一种共振隧穿二极管及其制作方法 (Resonant tunneling diode and manufacturing method thereof ) 是由 邱海兵 杨文献 边历峰 陆书龙 周祥鹏 于 2020-08-27 设计创作，主要内容包括：本发明公开了一种共振隧穿二极管,包括衬底以及在衬底上形成的外延部,外延部包括依序层叠在衬底上的第一势垒层、势阱层和第二势垒层,第一势垒层和第二势垒层均由AlN材料制成,势阱层由GaN材料制成。本发明还公开了一种共振隧穿二极管的制作方法。本发明解决了现有的共振隧穿二极管的功率较低的问题。(The invention discloses a resonant tunneling diode which comprises a substrate and an epitaxial part formed on the substrate, wherein the epitaxial part comprises a first barrier layer, a potential well layer and a second barrier layer which are sequentially stacked on the substrate, the first barrier layer and the second barrier layer are both made of AlN materials, and the potential well layer is made of GaN materials. The invention also discloses a manufacturing method of the resonant tunneling diode. The invention solves the problem of lower power of the existing resonant tunneling diode.)

1. A resonant tunneling diode comprising a substrate and an epitaxial portion formed on the substrate, wherein the epitaxial portion comprises a first barrier layer, a well layer and a second barrier layer which are sequentially stacked on the substrate, the first barrier layer and the second barrier layer are made of AlN material, and the well layer is made of GaN material.

2. A resonant tunneling diode according to claim 1, wherein the epitaxial portion further comprises a first ohmic contact layer disposed between the substrate and the first barrier layer and a second ohmic contact layer disposed on a surface of the second barrier layer facing away from the well layer; wherein the first ohmic contact layer and the second ohmic contact layer are both made of a GaN material.

3. A resonant tunneling diode according to claim 2, wherein the epitaxial portion further comprises a first isolation layer disposed between the first ohmic contact layer and the first barrier layer and a second isolation layer disposed between the second ohmic contact layer and the second barrier layer; wherein the first isolation layer is made of an AlGaN material, and the second isolation layer is made of a GaN material.

4. A resonant tunneling diode according to claim 3, wherein an orthographic projection of the first isolation layer, the first barrier layer, the well layer, the second barrier layer, the second isolation layer, and the second ohmic contact layer on the substrate are all within an orthographic projection of the first ohmic contact layer on the substrate.

5. The resonant tunneling diode of claim 4, wherein a passivation film is coated on the surface of the epitaxial portion, a first through hole is formed in the passivation film on the surface of the first ohmic contact layer facing the first isolation layer, a first electrode is disposed in the first through hole, a second through hole is formed in the passivation film on the second ohmic contact layer, and a second electrode is disposed in the second through hole.

6. A method for manufacturing a resonant tunneling diode, the method comprising:

sequentially stacking a first barrier layer, a potential well layer and a second barrier layer on the substrate by adopting a molecular beam epitaxy process;

the growth materials of the first barrier layer and the second barrier layer are AlN materials, and the growth material of the potential well layer is a GaN material.

7. The method of fabrication of claim 6, wherein prior to forming the first barrier layer, the method of fabrication further comprises: forming a first ohmic contact layer on the substrate; wherein the first barrier layer is formed on the first ohmic contact layer after the first ohmic contact layer is formed.

8. The method of manufacturing according to claim 7, wherein after forming the first ohmic contact layer, the method further comprises: forming a first isolation layer on the first ohmic contact layer; wherein the first barrier layer is formed on the first isolation layer after the first isolation layer is formed.

9. The method of fabrication of claim 8, wherein after forming the second barrier layer, the method of fabrication further comprises: and sequentially stacking a second isolation layer and a second ohmic contact layer on the second barrier layer.

10. The method of claim 9, wherein after forming the second ohmic contact layer, the method further comprises:

partially etching away the second ohmic contact layer, the second isolation layer, the second barrier layer, the potential well layer, the first barrier layer, the first isolation layer, and the first ohmic contact layer to form a mesa structure;

forming a passivation film on the surface of the mesa structure, and partially etching the passivation film to expose a portion of the second ohmic contact layer and a portion of the first ohmic contact layer;

and respectively growing a metal material on the exposed part of the second ohmic contact layer and the part of the first ohmic contact layer to form a first electrode and a second electrode.

Technical Field

The invention relates to the technical field of nano semiconductor devices, in particular to a resonant tunneling diode and a manufacturing method thereof.

Background

A third generation semiconductor material represented by GaN (gallium nitride) is attracting attention because of its excellent characteristics such as a large forbidden bandwidth, a high conduction band discontinuity, a high thermal conductivity, a high critical field strength, a high carrier saturation rate, and a high two-dimensional electron gas concentration at a heterojunction interface.

The GaN-based resonant tunneling diode (the potential well layer is made of the GaN material) made of the GaN material inherits the advantages of a heterojunction of GaN-based compound semiconductor materials, has the characteristics of high working frequency, high power, high temperature resistance and the like, and becomes a research hotspot in the field of nano devices.

At present, the materials commonly used in GaN-based resonant tunneling diodes include AlGaN materials and InAlN materials. The most easily grown barrier materials on the well layer of GaN material are indeed AlGaN material and InAlN material in view of lattice matching. However, the forbidden bandwidth of the AlGaN material changes with the change of the Al composition, which may cause the resonant tunneling effect of the resonant tunneling diode to be unstable, and further cause the power of the resonant tunneling diode to be insufficient. In the InAlN material, the In atoms have a larger atomic radius than the atoms thereof, and the activity difference is larger, so that the problems of phase separation and the like easily occur In the InAlN material, which directly causes the performance defect of the resonant tunneling diode.

Disclosure of Invention

In view of the disadvantages of the prior art, in one aspect of the present invention, a resonant tunneling diode is provided, which includes a substrate and an epitaxial portion formed on the substrate, the epitaxial portion including a first barrier layer, a well layer, and a second barrier layer sequentially stacked on the substrate, the first barrier layer and the second barrier layer each being made of AlN material, the well layer being made of GaN material.

Preferably, the epitaxial portion further includes a first ohmic contact layer disposed between the substrate and the first barrier layer, and a second ohmic contact layer disposed on a surface of the second barrier layer facing away from the well layer; wherein the first ohmic contact layer and the second ohmic contact layer are both made of a GaN material.

Preferably, the epitaxial portion further comprises a first isolation layer disposed between the first ohmic contact layer and the first barrier layer and a second isolation layer disposed between the second ohmic contact layer and the second barrier layer; wherein the first isolation layer is made of an AlGaN material, and the second isolation layer is made of a GaN material.

Preferably, the orthographic projections of the first isolation layer, the first barrier layer, the well layer, the second barrier layer, the second isolation layer, and the second ohmic contact layer on the substrate are all located within the orthographic projection of the first ohmic contact layer on the substrate.

Preferably, the epitaxial portion is wrapped up in the surface and is covered with the passive film, is located first ohmic contact layer is towards on the surface of first isolation layer be equipped with first through-hole on the passive film, be provided with first electrode in the first through-hole, be located on the second ohmic contact layer be equipped with the second through-hole on the passive film, be provided with the second electrode in the second through-hole.

In another aspect of the present invention, a method for manufacturing a resonant tunneling diode is provided, the method comprising:

sequentially stacking a first barrier layer, a potential well layer and a second barrier layer on the substrate by adopting a molecular beam epitaxy process;

the growth materials of the first barrier layer and the second barrier layer are AlN materials, and the growth material of the potential well layer is a GaN material.

Preferably, before forming the first barrier layer, the fabrication method further comprises: forming a first ohmic contact layer on the substrate; wherein the first barrier layer is formed on the first ohmic contact layer after the first ohmic contact layer is formed.

Preferably, after the first ohmic contact layer is formed, the manufacturing method further includes: forming a first isolation layer on the first ohmic contact layer; wherein the first barrier layer is formed on the first isolation layer after the first isolation layer is formed.

Preferably, after forming the second barrier layer, the fabrication method further includes: and sequentially stacking a second isolation layer and a second ohmic contact layer on the second barrier layer.

Preferably, after the second ohmic contact layer is formed, the manufacturing method further includes:

partially etching away the second ohmic contact layer, the second isolation layer, the second barrier layer, the potential well layer, the first barrier layer, the first isolation layer, and the first ohmic contact layer to form a mesa structure;

forming a passivation film on the surface of the mesa structure, and partially etching the passivation film to expose a portion of the second ohmic contact layer and a portion of the first ohmic contact layer;

and respectively growing a metal material on the exposed part of the second ohmic contact layer and the part of the first ohmic contact layer to form a first electrode and a second electrode.

Compared with the prior art, the AlN (aluminum nitride) material with larger lattice mismatch degree with the GaN material is selected as the barrier material of the resonant tunneling diode, and the larger band gap difference between the GaN material and the AlN material is utilized to form the higher barrier height of the resonant tunneling diode, so that the power of the resonant tunneling diode is improved. Meanwhile, a potential well layer made of a GaN material and a barrier layer made of an AlN material are grown by adopting a molecular beam epitaxy process, so that the problem of lattice mismatch between the GaN material and the AlN material is solved.

Drawings

Fig. 1 is a schematic structural diagram of a resonant tunneling diode according to an embodiment of the present invention;

fig. 2a to 2j are process diagrams of the resonant tunneling diode according to the embodiment of the invention.

Detailed Description

In the current GaN-based resonant tunneling diode field, defects of different degrees appear when a barrier layer is actually made of an AlGaN material and an InAlN material which are selected according to the lattice matching degree with a GaN material. For example: because the forbidden bandwidth of the AlGaN material changes with the change of the Al composition, when the AlGaN material is used to manufacture the barrier layer, the resonant tunneling diode has an unstable resonant tunneling effect, which directly causes the insufficient power of the resonant tunneling diode. In the InAlN material, the In atoms have a larger atomic radius than the atoms thereof, and the activity difference is larger, so that the problems of phase separation and the like easily occur In the InAlN material, which directly causes the performance defect of the resonant tunneling diode.

In view of the above problems, the present applicant found in the course of experiments that, although the lattice mismatch between the AlN material and the GaN material is large, the large lattice mismatch is due to the large band gap difference between the AlN material and the GaN material. However, in the field of resonant tunneling diodes, the larger the band gap difference between the well layer and the barrier layer, the higher the barrier height can be formed, and the higher the barrier height is beneficial to improving the power of the resonant tunneling diode. Therefore, although the lattice mismatch degree between the AlN material and the GaN material is large, the AlN material and the GaN material can be used to form a resonant tunneling diode with high power as long as the lattice mismatch between the AlN material and the GaN material is overcome. In subsequent research, the applicant has also found that the problem of lattice mismatch between the AlN material and the GaN material can be effectively overcome when the GaN material layer is grown on the AlN material layer or the AlN material layer is grown on the GaN material layer by using a molecular beam epitaxy process.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described in accordance with the drawings are exemplary only, and the invention is not limited to these embodiments. It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme according to the present invention are shown in the drawings, and other details not so relevant to the present invention are omitted. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element or a surface of another element, it can be directly on the other element or the surface of the other element or intervening elements may also be present. Alternatively, when an element is referred to as being "directly on" another element or a surface of another element, there are no intervening elements present.