JP2855222B2 - Semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device for emitting electrons, and more particularly to a semiconductor device capable of reducing the energy of emitted electrons to a desired level.

[Problems to be Solved by Conventional Techniques and Inventions] Conventionally, in order to emit electrons from a solid, it is general to emit thermal electrons by heating. Such a method is employed in the most popular CRT at present.

However, this method has a disadvantage that it can be used only for a large-sized one in principle. Further, in this method, the emitted electrons cannot be controlled, and in a cathode ray tube or the like, the emitted electrons are accelerated by applying an electric field to the desired energy. Therefore, it is not suitable for application to a small display element or a micro device.

The present invention has been made in view of such circumstances, and provides a semiconductor device capable of forming an electron emission device in a fine region and controlling the energy of the electrons. Aim.

[Means for Solving the Problems] The semiconductor device according to the present invention is configured such that the diluted magnetic semiconductor thin film and the semiconductor or insulator thin film become a quantum well, and the semiconductor or insulator thin film becomes a quantum barrier. It is characterized by comprising a multilayer film formed by lamination, an electrode for applying a voltage perpendicular to the film surface of the multilayer film, and a magnetic field applying means for applying a magnetic field to the multilayer film. . In this case, the multilayer film can have a super lattice structure.

[Operation] It is known that giant Zeeman splitting occurs in a diluted magnetic semiconductor (also referred to as a semi-magnetic semiconductor). Giant Zeeman splitting means that the energy level of a diluted magnetic semiconductor splits into an upward spin level and a downward spin level due to the presence of a magnetic field. In a multilayer film in which a diluted magnetic semiconductor thin film is used as a quantum well layer and a semiconductor or insulator thin film is used as a quantum barrier layer as in the present invention, the quantum well level, that is, the resonance tunnel energy is proportional to the magnitude of the applied magnetic field. Can be changed. Therefore, the energy of the emitted electrons can be controlled by the voltage applied perpendicular to the film surface of the multilayer film and the magnetic field.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention. The substrate 1 is formed of an insulator that does not change with time, such as glass, and a first electrode 2, a multilayer film 3 having a quantum well structure, and a second electrode 4 are formed on the substrate 1. They are formed in order.

The multilayer film 3 is formed by alternately stacking quantum well layers 3a and quantum barrier layers 3b. The quantum well layer 3a is formed of a dilute magnetic semiconductor, and the quantum barrier layer 3b is formed of a semiconductor or an insulator. I have. The multilayer film 3 is not limited to the superlattice structure as shown in FIG.
That is, the structure may be a three-layer film in which the quantum well layer 3a is sandwiched between the quantum barrier layers 3b.

The dilute magnetic semiconductor constituting the quantum well layer 3a, for example, there is Cd _1-x Mn _x Te, as the semiconductor or insulator constituting the quantum barrier layer 3b, for example ZnS, there is SiC.

In this case, the energy level of the quantum well layer can be set to a target value by appropriately adjusting the composition ratio x of the diluted magnetic semiconductor or the thickness of the well layer 3a.

A magnetic field of a desired magnitude is applied to the multilayer film 3 by a magnetic field applying device (not shown).

A power supply 5 is connected to the electrodes 2 and 4. When the power supply 5 is turned on, a voltage is applied vertically to the film surface of the multilayer film 3 via the electrodes 2 and 4.

Next, the operation of the semiconductor device thus configured will be described. FIG. 2 schematically shows an energy level of a quantum well layer composed of a diluted magnetic semiconductor.
The quantum well level E when the magnetic field is zero is as shown in FIG. This energy level can be set to a desired value by adjusting the composition or film thickness of the diluted magnetic semiconductor as described above. Here, for simplicity, only one level is shown. When a magnetic field is applied to the multilayer film 3 in such a state, giant Zeeman splitting occurs as shown in FIG. 2 (b), and the energy level splits by giant Zeeman energy (ΔE). The energy level changes in proportion to. Therefore, by applying a magnetic field to the multilayer film by the magnetic field applying device and changing the value of the applied magnetic field, the energy level of the well layer, that is, the resonance tunnel energy can be changed by applying the magnetic field.

When a predetermined voltage is applied between the electrodes 2 and 4 while a predetermined magnetic field is applied, electrons are emitted from the cathode side (the second electrode 4 in FIG. 1). In this case, as described above, since the resonance tunnel energy can be adjusted by the value of the magnetic field, the energy of the emitted electrons can be controlled. That is, it is possible to obtain an electron emission device capable of controlling the energy of the emitted electrons by the magnetic field and the electric field.

[Effects of the Invention] According to the present invention, a completely novel semiconductor as an electron emitter that can be manufactured by ordinary semiconductor fine processing technology and that can control the energy of emitted electrons by utilizing the giant Zeeman splitting of a diluted magnetic semiconductor. A device can be obtained. Further, the semiconductor device according to the present invention can detect a magnetic field in a minute region, is effective for reading various magnetic memories, and is also useful in the field of display elements.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is an energy band diagram of a multilayer film. 1; substrate; 2, 4; electrode; 3; multilayer film; 3a; quantum well layer (dilute magnetic semiconductor thin film); 3b; quantum barrier layer (semiconductor or insulator thin film).

Claims (2)

(57) [Claims] 1. A multilayer film comprising a thin magnetic semiconductor thin film and a semiconductor or insulator thin film laminated such that the thin magnetic semiconductor thin film becomes a quantum well and the semiconductor or insulator thin film becomes a quantum barrier. A semiconductor device comprising: an electrode for applying a voltage perpendicular to a film surface of a film; and a magnetic field applying unit for applying a magnetic field to the multilayer film. 2. The semiconductor device according to claim 1, wherein said multilayer film has a superlattice structure.