JPH01186672A - Schottky junction structure - Google Patents

Abstract

PURPOSE:To make it possible to control the height of Schottky barrier by shaping a kind of metal having a large chemical combination energy with III-V compound semiconductor in a specified thickness before forming another kind of metal on the surface of III-V compound semiconductor. CONSTITUTION:Between metal 3 and III-V compound semiconductor 1, another kind of metal 2 having a large chemical combination energy with the semiconductor 1 is formed as thick as a 1/10-30atoms thick layer. Consequently, the strong chemical combination between the metal 2 and the semiconductor assures a sharp and stable interface. As a result, development of defects in the semiconductor 1 which is regarded to cause pinning of Fermi level is restrained and, therefore, the Schottky barrier is not a definite value but decided based on work function of the metal 2. The height of the Schottky barrier of the semiconductor 1 can be thereby controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a Schottky junction structure in which the Schottky barrier height of a semiconductor can be controlled.

(Prior art) It was thought that the height of the Schottky barrier when a single metal is brought into contact with a semiconductor is ideally given by the difference between the work function of the metal and the electron affinity of the semiconductor [Physics. Of Semiconductor Devices (Physics)
of Sem1conductorDevices.

1969, John Wiley R5ons, In
c, )], therefore, in order to change the height of the Schottky barrier for any semiconductor, it would be sufficient to contact it with metals with different work functions. However, depending on the type of semiconductor, even if metals with different work functions are brought into contact,
In some cases, the Fermi level was fixed (pinned) to a constant value, making it impossible to change the height of the Schottky barrier.

IV group bioconductors with high industrial utility value were a notable example [Physical Review Letters (Phys.
Rev, Lett, ) Volume 22, 1969, No. 1
433 pages].

(Problems to be Solved by the Invention) The height of the Schottky barrier is preferably higher, for example, in order to improve rectification characteristics, and lower, in order to reduce contact resistance. Furthermore, the height of the Schottky barrier is an important factor determining the threshold voltage of a transistor. Therefore, as mentioned above, the inability to control the height of the Shortkey barrier in the ■-V group compound semiconductor, which has high utility value, has been a major handicap in device design.

An object of the present invention is to provide a Schottky junction structure in which the height of the Schottky barrier of a semiconductor can be controlled.

(Means for Solving the Problems) The present invention provides a Schottky junction structure of a metal and a -V group compound semiconductor, in which a different metal having a large chemical bond energy with the semiconductor is present between the metal and the semiconductor. 1/
It is characterized by being formed to a thickness of 10 to 30 atomic layers.

(Function) The present inventor has discovered that whether or not the Fermi level is pinned at the metal/I[IV group compound semiconductor interface is determined when a metal with a thickness of about one atomic layer is brought into contact (Journal. of Vacuum Science and Technology (J, Vac, Sci, Te-channel,
), Vol. 17, 1980, p. 1019), and the work function of a metal does not reach its bulk state value when the layer thickness is about 1-degree, but reaches its bulk state value only when the layer thickness becomes about 30 layers. What to do cheaply (Journal of Vacuum Science and Technology (J, Vac,
Set, Technol, ) Volume 16, 1979
Year.

(page 1137).

If there is even a single metal that does not pin the Fermi level when it comes into contact with the ■-V compound semiconductor, then bring that metal into contact with the ■-V group compound semiconductor by 1/10 to 30 atomic layers, and then When 30 or more atomic layers of arbitrary metals are brought into contact, the barrier height of the Schottky junction formed at that time is thought to be determined by the work function of the latter metal, not by the work function of the former metal. .

For example, when searching for a metal that does not pin the Fermi level of GaAs, it was reported that sb was such a metal (Journal of Vacuum Science and Technology (J, V
ac, Sci, Technol,) Volume A4, 1
986, p. 958).

Therefore, as shown in FIG. 1, one atomic layer of Sb2 was formed on a clean GaAs substrate 1, and subsequently, an arbitrary metal 3 of 30A or more was formed.

The strong chemical bond between sb and GaAs ensures a steep and stable interface, thereby suppressing the occurrence of defects in the semiconductor and interdiffusion between metal and semiconductor, which are thought to cause Fermi-level pinning. It was found that the Schottky barrier is not determined by a fixed value but by the work function of the metal. Such an effect has also been found in other metals that have strong chemical bonds with GaAs, such as Dy and Sc.

The present invention will be explained in detail below.

The Schottky junction structure of the present invention was formed using a supporting metal sb and a GaAs semiconductor, and the dependence of the Schottky barrier height on the work function of the metal was investigated. I was able to control it. The experiment is n
A type GaAs (110) substrate is cleaved in an ultra-high vacuum, and sb is deposited on its surface at room temperature to a thickness of 1/10 atomic by molecular beam epitaxial growth. Subsequently, 50OA of metal such as Au, Pd, At, and Ti was vapor-deposited thereon. After placing the electrodes on the prepared sample, C
−■Evaluation was performed using the measuring method, and the Schottky barrier height was determined. As a result, the Schottky barrier height was 1500 m, reflecting the difference in the work functions of these four metals.
eV also changed. This value reached 30 times the conventional barrier height variation range.

The Schottky junction structure of the present invention was formed using a supporting metal Sc and an InP semiconductor, and the dependence of the Schottky barrier height on the work function of the metal was investigated. We were able to. An experimental n-type I n P (110) substrate was cleaved in ultra-high vacuum;
A 30 atomic layer of Sc was deposited on the surface at room temperature by molecular beam epitaxial growth. Subsequently, 100 pieces each of Au, Pd, AI, and Mn were added as various metals on top of it.
Deposited.

After attaching an electrode to the prepared sample, it was evaluated by the C-■ measurement method to determine the Schottky barrier height. As a result, the Schottky barrier height is 1020 m e
V has also changed. This value is 12% of the conventional barrier height variation range.
It has doubled.

When the Schottky junction structure of the present invention was formed using a metal I)y and a GaAs semiconductor and the Schottky barrier height was measured, it was found that the Schottky barrier height changed significantly compared to the conventional structure. I was able to do that. The experiment was conducted using n-type GaAs (
100) Three atomic layers of [)y were deposited on the substrate by molecular beam epitaxial growth at room temperature. Subsequently, AI was deposited thereon at 1000A. Then, an electrode was attached to the prepared sample, and the Schottky barrier height was determined by evaluating the sample using the C-■ measurement method. As a result, it was found that the Schottky barrier height was reduced by 150 meV compared to 75 meV for the conventional A I I nGaAs sidewall, and the Fermi level was not pinned.

In this example, Sb and Sc are used as metals with large chemical bonds by molecular beam epitaxial growth.

Although the case where D and y are grown on InP and GaAs is shown, the effects of the present invention are not dependent on the growth method or the type of metal. Any material that has a strong chemical bonding force with the substrate on a clean ■-■ group substrate may be used. ■-V group compounds are not limited to InP and GaAS (InGaS).
It can also be applied to As, InGaP, etc. .

(Effects of the Invention) As explained above, in the ■-V group compound semiconductor Schottky junction, the present invention provides chemical bonding with the II-V group compound semiconductor before metal is formed on the ■-V group compound semiconductor surface. By forming a different metal with high energy to a thickness of 1/10 to 30 atomic layers on a III-V group compound semiconductor, the Schottky barrier height can be controlled by the work function of the metal rather than a fixed value. It has a positive effect.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing a Schottky junction structure according to the present invention. 1...GaAs 2...sb 3...Any metal

Claims (1)

[Claims] (1) In a metal and III-V compound semiconductor Schottky junction structure, between the metal and the semiconductor, a different metal having a large chemical bond energy with the semiconductor is 1/1
A Schottky junction structure characterized by being formed to a thickness of 0 to 30 atomic layers.