CN103400866B

CN103400866B - GaN Schottky diode based on modulation doping

Info

Publication number: CN103400866B
Application number: CN201310328121.4A
Authority: CN
Inventors: 梁士雄; 冯志红; 房玉龙; 邢东; 王俊龙; 张立森; 杨大宝
Original assignee: CETC 13 Research Institute
Current assignee: CETC 13 Research Institute
Priority date: 2013-07-31
Filing date: 2013-07-31
Publication date: 2016-12-28
Anticipated expiration: 2033-07-31
Also published as: CN103400866A

Abstract

The invention discloses a kind of GaN Schottky diode based on modulation doping, belong to field of semiconductor devices.The present invention includes the semi-insulated substrate layer for supporting whole GaN Schottky diode, the highly doped N+ type GaN layer grown on substrate layer, and uses the N type GaN layer of modulation doping growth in N+ type GaN layer；The doping content of N type GaN layer starts non-uniform Distribution from the interface of N+ type GaN layer；N+ type GaN layer grows Ohm contact electrode；In N type GaN layer, growth has Schottky contact electrode.The present invention utilizes modulation doping mode to grow N type GaN layer in N+ type GaN layer, improve the mobility of GaN material, improve distribution of electron's density in material, reduce the schottky junction electric capacity of diode, improve its operating frequency, and then improve operating frequency and the output of frequency multiplier circuit in the range of millimeter wave and Terahertz；Can effectively control the variable compression ratio of Schottky diode by controlling modulation doping, improve the Q-value of device.

Description

GaN Schottky diode based on modulation doping

Technical field

The invention belongs to field of semiconductor devices.

Background technology

Schottky frequency doubled diode device based on the conventional semiconductor material such as Si, GaAs, owing to being limited by the attribute of material own, is difficult to have further raising on power and the corresponding index such as breakdown voltage resistant again.Semiconductor material with wide forbidden band of new generation development with III group-III nitride as table is swift and violent in recent years.There is the superior material properties such as broad-band gap, high saturated electrons drift speed, high breakdown field strength and high heat conductance, in millimeter wave, the great development potentiality in submillimeter wave high-power electronic device field.Schottky variable capacitance diode millimeter wave based on GaN, the research of submillimeter wave frequency doubling device are current international focuses, and domestic research also rests on the lowest frequency band.

Due to the electron mobility of GaN material, to compare GaAs ratio relatively low, and the series resistance of the Schottky diode prepared based on GaN material is the biggest so that the cut-off frequency of device and operating frequency are extremely difficult to the level of GaAs base device.It addition, the wet corrosion technique of GaN material is the most immature, typically uses dry etching, then carry out planarization process, device technology is brought difficulty.Using at present and improve ohmic contact craft and explore new Schottky contact metal to improve the operating frequency of device, operating frequency is the highest in the world has reached 100GHz.Need to start with from material and device architecture to improve the operating frequency of device further, improve the mobility of GaN material, use planarized structure conventional for GaAs, reach higher operating frequency.

The method using modulation doping can change the distribution of electron concentration, improves the variable compression ratio of Schottky diode, reduces the advantage of schottky junction electric capacity.But the most do not carry out the work of the Schottky diode of modulation doping GaN material both at home and abroad.

Summary of the invention

It is an object of the invention to provide a kind of GaN Schottky diode based on modulation doping, N-type GaN layer of the present invention and N+ type GaN layer vertically grow, and N-type GaN layer uses modulation doping mode to grow, the variable compression ratio of GaN Schottky variable capacitance diode can be improved, reduce junction capacity, improve operating frequency and the output of frequency multiplier circuit in the range of millimeter wave and Terahertz.

For solving above-mentioned technical problem, the technical solution used in the present invention is: a kind of GaN Schottky diode based on modulation doping, including the semi-insulated substrate layer for supporting whole GaN Schottky diode, on described substrate layer growth highly doped N+ type GaN layer, and the N-type GaN layer that employing modulation doping grows in described N+ type GaN layer, the doping content of N-type GaN layer starts as non-uniform Distribution from the interface of N+ type GaN layer；Described N+ type GaN layer grows Ohm contact electrode；In described N-type GaN layer, growth has Schottky contact electrode.

The variation pattern of the doping content of described N-type GaN layer for being incremented by from top to bottom, successively decrease from top to bottom, exponential or Gauss distribution.

The doped chemical of described N-type GaN layer is IV race's element, and doping content is 10¹⁶/cm³Magnitude is to 10¹⁸/cm³Between magnitude.

Described substrate layer includes Sapphire Substrate, silicon carbide substrates or silicon substrate.

The doped chemical of described N+ type GaN layer is IV race's element, and doping content is 10¹⁶/cm³To 10¹⁹/cm³。

The technological progress using technique scheme to obtain is:

1, the present invention utilizes modulation doping mode to grow N-type GaN layer in N+ type GaN layer, improves the electron mobility of GaN material, improves distribution of electron's density in material, reduces the schottky junction electric capacity of diode, improve its operating frequency；

2, can effectively control the variable compression ratio of Schottky diode, and then the Q-value of raising device by controlling modulation doping, and improve the shg efficiency of device.

Accompanying drawing explanation

Fig. 1 is the structural representation of the present invention；

Wherein, 101, substrate layer, 102, N+ type GaN layer, 103, N-type GaN layer, 104, Ohm contact electrode, 105, Schottky contact electrode.

Detailed description of the invention

Understand as shown in Figure 1, GaN Schottky diode based on modulation doping, including the semi-insulated substrate layer 101 for supporting whole GaN Schottky diode, on described substrate layer 101 growth highly doped N+ type GaN layer 102, and in described N+ type GaN layer 102 use modulation doping growth N-type GaN layer 103；The doped chemical of described N-type GaN layer 103 is IV race's element, and doping content is 10¹⁶/cm³Magnitude is to 10¹⁸/cm³Between magnitude；The variation pattern of the doping content of described N-type GaN layer 103 is for being incremented by from top to bottom or successively decreasing from top to bottom.

The doped chemical of described N+ type GaN layer 102 is IV race's element, and doping content is 10¹⁶/cm³To 10¹⁹/cm³。

In described N+ type GaN layer 102, growth has Ohm contact electrode 104, Ohm contact electrode 104 to be divided into two parts, is symmetrically set in the both ends of N+ type GaN layer 102, and between Ohm contact electrode 104 with N+ type GaN layer 102, face contacts.In described N-type GaN layer 103, growth has Schottky contact electrode 105, Schottky contact electrode 105 to contact with N-type GaN layer 103.

In the present embodiment, substrate layer 101 is Sapphire Substrate layer；Described Ohm contact electrode 104 is formed by high temperature rapid thermal annealing by evapontte ie meti yer, and this evapontte ie meti yer is formed by the titanium being sequentially depositing, aluminum, nickel, gold；The evapontte ie meti yer that described Schottky contact electrode 105 is precipitated successively by titanium, platinum, gold is formed.

The making step of this Schottky diode is:

1, semi-insulated substrate layer 101 is prepared；

2, in the N+ type GaN layer 102 that substrate layer 101 Epitaxial growth is highly doped, doped chemical is IV race's element, and such as Si element, doping content controls 10¹⁶/cm³To 10¹⁹/cm³Between；

3, using polarization doping method epitaxial growth N-type GaN layer 103 in N+ type GaN layer 102, the doped chemical of this N-type GaN layer 103 is IV race's element, its doping content increasing or decreasing the most successively, but doping content controls 10¹⁶/cm³Magnitude is to 10¹⁸/cm³Between magnitude；

4, the part at N-type GaN layer 103 two ends is removed by wet etching or dry etch process, expose N+ type GaN layer 102, step is formed between N-type GaN layer 103 and N+ type GaN layer 102, exposed N+ type GaN layer 102 use electron beam evaporation method evapontte ie meti yer make Ohm contact electrode 104, be specially precipitate successively titanium, aluminum, nickel, gold, and under 800 degree to 900 degree, carry out alloy with quick anneal oven, to reduce the resistivity of Ohm contact electrode 104；

5. expose N-type GaN layer 103, deposited by electron beam evaporation method evaporated metal, specially titanium, platinum, gold by the method for photoetching, form Schottky contact electrode 105 on N-type GaN layer 103 surface of polarization doping.

Embodiment 2

As different from Example 1, described N-type GaN layer 103 begins with the non-linear growth of gradient doping method from the interface of N+ type GaN layer 102, the variation pattern Gaussian distributed of doping content or exponential can also be other nonlinear Distribution, such as t-distribution, Γ distribution etc..

In the present embodiment, substrate layer 101 can also be other semi-conducting materials such as Si for SiC.

The present invention utilizes modulation doping mode to grow N-type GaN layer in N+ type GaN layer, improve distribution of electron's density in material, improve the mobility of GaN material, reduce the schottky junction electric capacity of diode, improve its operating frequency, and then improve operating frequency and the output of frequency multiplier circuit in the range of millimeter wave and Terahertz；Can effectively control the variable compression ratio of Schottky diode by controlling modulation doping, improve the Q-value of device, and then improve the shg efficiency of device.

Presents only describes the structure of the underlying diode with this class formation, Ohm contact electrode and Schottky contact electrode is arranged position and is described, and those skilled in the art can go out various forms of device according to the extensibility of structure of the present invention.

Claims

1. a GaN Schottky diode based on modulation doping, it is characterized in that the semi-insulated substrate layer (101) included for supporting whole GaN Schottky diode, highly doped N+ type GaN layer (102) in the upper growth of described substrate layer (101), and in the upper N-type GaN layer (103) using modulation doping growth of described N+ type GaN layer (102), the doping content of N-type GaN layer (103) starts as non-uniform Distribution from the interface of N+ type GaN layer (102), the variation pattern of the doping content of described N-type GaN layer (103) is for be incremented by from top to bottom, successively decrease from top to bottom, exponential or Gauss distribution；Described N+ type GaN layer (102) grows Ohm contact electrode (104)；Schottky contact electrode (105) is had in the upper growth of described N-type GaN layer (103).

GaN Schottky diode based on modulation doping the most according to claim 1, it is characterised in that the doped chemical of described N-type GaN layer (103) is IV race's element, and doping content is 10¹⁶/cm³Magnitude is to 10¹⁸/cm³Between magnitude.

GaN Schottky diode based on modulation doping the most according to claim 1, it is characterised in that described substrate layer (101) includes Sapphire Substrate, silicon carbide substrates or silicon substrate.

GaN Schottky diode based on modulation doping the most according to claim 1, it is characterised in that the doped chemical of described N+ type GaN layer (102) is IV race's element, doping content is 10¹⁶cm^-3To 10¹⁹cm^-3。